diff --git a/ext/src/cast/sdk/Session.ts b/ext/src/cast/sdk/Session.ts
index 3d3e3e2..4401964 100644
--- a/ext/src/cast/sdk/Session.ts
+++ b/ext/src/cast/sdk/Session.ts
@@ -5,13 +5,13 @@ import { v4 as uuid } from "uuid";
 import logger from "../../lib/logger";
 
 import eventMessaging from "../pageMessenging";
+import { convertSupportedMediaCommandsFlags } from "../utils";
 
-import {
+import type {
     MediaStatus,
     ReceiverMediaMessage,
     SenderMediaMessage,
-    SenderMessage,
-    _MediaCommand
+    SenderMessage
 } from "./types";
 
 import { SessionStatus } from "./enums";
@@ -22,9 +22,13 @@ import type {
     SenderApplication
 } from "./classes";
 
-import { MediaCommand } from "./media/enums";
 import type { LoadRequest, QueueLoadRequest, QueueItem } from "./media/classes";
-import Media, { NS_MEDIA } from "./media/Media";
+import Media, {
+    createMedia,
+    MediaLastUpdateTimes,
+    MediaUpdateListeners,
+    NS_MEDIA
+} from "./media/Media";
 
 /**
  * Takes a media object and a media status object and merges the status
@@ -32,7 +36,7 @@ import Media, { NS_MEDIA } from "./media/Media";
  */
 function updateMedia(media: Media, status: MediaStatus) {
     if (status.currentTime) {
-        media._lastUpdateTime = Date.now();
+        MediaLastUpdateTimes.set(media, Date.now());
     }
 
     // Copy basic props
@@ -46,23 +50,9 @@ function updateMedia(media: Media, status: MediaStatus) {
     if (status.repeatMode) media.repeatMode = status.repeatMode;
     if (status.volume) media.volume = status.volume;
 
-    // Convert supportedMediaCommands bitflags to string array
-    const supportedMediaCommands: string[] = [];
-    if (status.supportedMediaCommands & _MediaCommand.PAUSE) {
-        supportedMediaCommands.push(MediaCommand.PAUSE);
-    } else if (status.supportedMediaCommands & _MediaCommand.SEEK) {
-        supportedMediaCommands.push(MediaCommand.SEEK);
-    } else if (status.supportedMediaCommands & _MediaCommand.STREAM_VOLUME) {
-        supportedMediaCommands.push(MediaCommand.STREAM_VOLUME);
-    } else if (status.supportedMediaCommands & _MediaCommand.STREAM_MUTE) {
-        supportedMediaCommands.push(MediaCommand.STREAM_MUTE);
-    } else if (status.supportedMediaCommands & _MediaCommand.QUEUE_NEXT) {
-        supportedMediaCommands.push("queue_next");
-    } else if (status.supportedMediaCommands & _MediaCommand.QUEUE_PREV) {
-        supportedMediaCommands.push("queue_prev");
-    }
-
-    media.supportedMediaCommands = supportedMediaCommands;
+    media.supportedMediaCommands = convertSupportedMediaCommandsFlags(
+        status.supportedMediaCommands
+    );
 
     // Update queue state
     if (status.items) {
@@ -97,21 +87,57 @@ function updateMedia(media: Media, status: MediaStatus) {
     }
 }
 
+export const SessionMessageListeners = new WeakMap<
+    Session,
+    Map<string, Set<MessageListener>>
+>();
+export const SessionUpdateListeners = new WeakMap<
+    Session,
+    Set<UpdateListener>
+>();
+export const SessionSendMessageCallbacks = new WeakMap<
+    Session,
+    Map<string, SendMessageCallback>
+>();
+
+/** Creates a Session object and initializes private data. */
+export function createSession(
+    sessionArgs: ConstructorParameters<typeof Session>
+) {
+    const session = new Session(...sessionArgs);
+    SessionUpdateListeners.set(session, new Set());
+    SessionSendMessageCallbacks.set(session, new Map());
+
+    return session;
+}
+
 type MessageListener = (namespace: string, message: string) => void;
 type UpdateListener = (isAlive: boolean) => void;
+type SendMessageCallback = [(() => void)?, ((err: CastError) => void)?];
 
 export default class Session {
     #loadMediaRequest?: LoadRequest;
     #loadMediaSuccessCallback?: (media: Media) => void;
     #loadMediaErrorCallback?: (err: CastError) => void;
 
-    _messageListeners = new Map<string, Set<MessageListener>>();
-    _updateListeners = new Set<UpdateListener>();
-
-    _sendMessageCallbacks = new Map<
-        string,
-        [(() => void)?, ((err: CastError) => void)?]
-    >();
+    get #messageListeners() {
+        const messageListeners = SessionMessageListeners.get(this);
+        if (!messageListeners)
+            throw logger.error("Missing session message listeners!");
+        return messageListeners;
+    }
+    get #updateListeners() {
+        const updateListeners = SessionUpdateListeners.get(this);
+        if (!updateListeners)
+            throw logger.error("Missing session update listeners!");
+        return updateListeners;
+    }
+    get #sendMessageCallbacks() {
+        const sendMessageCallback = SessionSendMessageCallbacks.get(this);
+        if (!sendMessageCallback)
+            throw logger.error("Missing session sendMessage callback!");
+        return sendMessageCallback;
+    }
 
     media: Media[] = [];
     namespaces: Array<{ name: string }> = [];
@@ -129,6 +155,7 @@ export default class Session {
     ) {
         this.transportId = sessionId || "";
 
+        SessionMessageListeners.set(this, new Map());
         this.addMessageListener(NS_MEDIA, this.#mediaMessageListener);
     }
 
@@ -147,9 +174,8 @@ export default class Session {
 
                     // Handle Media creation
                     if (!media) {
-                        media = new Media(
-                            this.sessionId,
-                            mediaStatus.mediaSessionId,
+                        media = createMedia(
+                            [this.sessionId, mediaStatus.mediaSessionId],
                             this.#sendMediaMessage
                         );
 
@@ -158,8 +184,11 @@ export default class Session {
                         this.#loadMediaSuccessCallback?.(media);
                     } else {
                         updateMedia(media, mediaStatus);
-                        for (const listener of media._updateListeners) {
-                            listener(true);
+                        const updateListeners = MediaUpdateListeners.get(media);
+                        if (updateListeners) {
+                            for (const listener of updateListeners) {
+                                listener(true);
+                            }
                         }
                     }
                 }
@@ -198,7 +227,7 @@ export default class Session {
                 }
             });
 
-            this._sendMessageCallbacks.set(messageId, [resolve, reject]);
+            this.#sendMessageCallbacks.set(messageId, [resolve, reject]);
         });
     };
 
@@ -210,21 +239,21 @@ export default class Session {
     }
 
     addMessageListener(namespace: string, listener: MessageListener) {
-        if (!this._messageListeners.has(namespace)) {
-            this._messageListeners.set(namespace, new Set());
+        if (!this.#messageListeners.has(namespace)) {
+            this.#messageListeners.set(namespace, new Set());
         }
 
-        this._messageListeners.get(namespace)?.add(listener);
+        this.#messageListeners.get(namespace)?.add(listener);
     }
     removeMessageListener(namespace: string, listener: MessageListener) {
-        this._messageListeners.get(namespace)?.delete(listener);
+        this.#messageListeners.get(namespace)?.delete(listener);
     }
 
     addUpdateListener(listener: UpdateListener) {
-        this._updateListeners.add(listener);
+        this.#updateListeners.add(listener);
     }
     removeUpdateListener(listener: UpdateListener) {
-        this._updateListeners.delete(listener);
+        this.#updateListeners.delete(listener);
     }
 
     leave(
@@ -272,7 +301,7 @@ export default class Session {
             }
         });
 
-        this._sendMessageCallbacks.set(messageId, [
+        this.#sendMessageCallbacks.set(messageId, [
             successCallback,
             errorCallback
         ]);
diff --git a/ext/src/cast/sdk/classes.ts b/ext/src/cast/sdk/classes.ts
index 15ad45f..866b1de 100644
--- a/ext/src/cast/sdk/classes.ts
+++ b/ext/src/cast/sdk/classes.ts
@@ -6,6 +6,7 @@ import {
     AutoJoinPolicy,
     Capability,
     DefaultActionPolicy,
+    ErrorCode,
     ReceiverAvailability,
     ReceiverType,
     VolumeControlType
@@ -35,7 +36,7 @@ export class DialRequest {
 
 export class Error {
     constructor(
-        public code: string,
+        public code: ErrorCode,
         public description: Nullable<string> = null,
         public details: unknown = null
     ) {}
diff --git a/ext/src/cast/sdk/index.ts b/ext/src/cast/sdk/index.ts
index 359a674..de79b0d 100644
--- a/ext/src/cast/sdk/index.ts
+++ b/ext/src/cast/sdk/index.ts
@@ -33,9 +33,14 @@ import {
     Volume
 } from "./classes";
 
-import Session from "./Session";
+import Session, {
+    createSession,
+    SessionMessageListeners,
+    SessionSendMessageCallbacks,
+    SessionUpdateListeners
+} from "./Session";
 
-import media from "./media";
+import * as media from "./media";
 
 type ReceiverActionListener = (
     receiver: Receiver,
@@ -49,6 +54,7 @@ export default class {
     #apiConfig?: ApiConfig;
     #sessionRequest?: SessionRequest;
 
+    /** Current receiver availability. */
     #receiverAvailability = ReceiverAvailability.UNAVAILABLE;
 
     #initializeSuccessCallback?: () => void;
@@ -87,7 +93,7 @@ export default class {
     Volume = Volume;
     Session = Session;
 
-    media = media;
+    media = { ...media };
 
     VERSION = [1, 2];
     isAvailable = false;
@@ -101,10 +107,19 @@ export default class {
         switch (message.subject) {
             case "cast:initialized":
                 this.isAvailable = true;
-
                 this.#initializeSuccessCallback?.();
                 this.#apiConfig?.receiverListener(this.#receiverAvailability);
+                break;
 
+            // Popup closed before session established
+            case "cast:sessionRequestCancelled":
+                if (this.#sessionRequest) {
+                    this.#sessionRequest = undefined;
+
+                    this.#requestSessionErrorCallback?.(
+                        new CastError(ErrorCode.CANCEL)
+                    );
+                }
                 break;
 
             /**
@@ -120,13 +135,13 @@ export default class {
                     status.appImages
                 );
 
-                const session = new Session(
+                const session = createSession([
                     status.sessionId,
                     status.appId,
                     status.displayName,
                     status.appImages,
                     status.receiver
-                );
+                ]);
 
                 session.namespaces = status.namespaces;
                 session.senderApps = status.senderApps;
@@ -164,8 +179,11 @@ export default class {
                 session.namespaces = status.namespaces;
                 session.receiver.volume = status.volume;
 
-                for (const listener of session._updateListeners) {
-                    listener(session.status !== SessionStatus.STOPPED);
+                const updateListeners = SessionUpdateListeners.get(session);
+                if (updateListeners) {
+                    for (const listener of updateListeners) {
+                        listener(session.status !== SessionStatus.STOPPED);
+                    }
                 }
 
                 break;
@@ -176,8 +194,12 @@ export default class {
                 const session = this.#sessions.get(sessionId);
                 if (session) {
                     session.status = SessionStatus.STOPPED;
-                    for (const listener of session._updateListeners) {
-                        listener(false);
+
+                    const updateListeners = SessionUpdateListeners.get(session);
+                    if (updateListeners) {
+                        for (const listener of updateListeners) {
+                            listener(false);
+                        }
                     }
                 }
 
@@ -188,7 +210,8 @@ export default class {
                 const { sessionId, namespace, messageData } = message.data;
                 const session = this.#sessions.get(sessionId);
                 if (session) {
-                    const listeners = session._messageListeners.get(namespace);
+                    const listeners =
+                        SessionMessageListeners.get(session)?.get(namespace);
                     if (listeners) {
                         for (const listener of listeners) {
                             listener(namespace, messageData);
@@ -207,12 +230,16 @@ export default class {
                     break;
                 }
 
-                const callbacks = session._sendMessageCallbacks.get(messageId);
-                if (callbacks) {
-                    const [successCallback, errorCallback] = callbacks;
+                const sendMessageCallback =
+                    SessionSendMessageCallbacks.get(session)?.get(messageId);
+                if (sendMessageCallback) {
+                    const [successCallback, errorCallback] =
+                        sendMessageCallback;
 
                     if (error) {
-                        errorCallback?.(new CastError(error));
+                        errorCallback?.(
+                            new CastError(ErrorCode.CHANNEL_ERROR, error)
+                        );
                         return;
                     }
 
@@ -236,26 +263,11 @@ export default class {
                 break;
             }
 
-            // Popup closed before session established
-            case "cast:sessionRequestCancelled": {
-                if (this.#sessionRequest) {
-                    this.#sessionRequest = undefined;
-
-                    this.#requestSessionErrorCallback?.(
-                        new CastError(ErrorCode.CANCEL)
-                    );
-                }
-
-                break;
-            }
-
-            case "cast:receiverAction": {
+            case "cast:receiverAction":
                 for (const actionListener of this.#receiverActionListeners) {
                     actionListener(message.data.receiver, message.data.action);
                 }
-
                 break;
-            }
         }
     }
 
diff --git a/ext/src/cast/sdk/media/Media.ts b/ext/src/cast/sdk/media/Media.ts
index b1b8658..db568e2 100644
--- a/ext/src/cast/sdk/media/Media.ts
+++ b/ext/src/cast/sdk/media/Media.ts
@@ -2,9 +2,15 @@
 
 import { v4 as uuid } from "uuid";
 
-import logger from "../../../lib/logger";
+import { Logger } from "../../../lib/logger";
+const logger = new Logger("fx_cast [sdk :: cast.Media]");
+
+import { getEstimatedTime } from "../../utils";
+import type { SenderMediaMessage } from "../types";
 
 import { Volume, Error as CastError } from "../classes";
+import { ErrorCode } from "../enums";
+
 import {
     BreakStatus,
     EditTracksInfoRequest,
@@ -26,23 +32,52 @@ import {
     VideoInformation,
     VolumeRequest
 } from "./classes";
-
 import { PlayerState, RepeatMode } from "./enums";
-import { ErrorCode } from "../enums";
-
-import type { SenderMediaMessage } from "../types";
-import { getEstimatedTime } from "../../utils";
 
 export const NS_MEDIA = "urn:x-cast:com.google.cast.media";
 
+type MediaMessageCallback = (
+    message: DistributiveOmit<SenderMediaMessage, "requestId">
+) => Promise<void>;
+
+const MediaMessageCallbacks = new WeakMap<Media, MediaMessageCallback>();
+export const MediaUpdateListeners = new WeakMap<Media, Set<UpdateListener>>();
+export const MediaLastUpdateTimes = new WeakMap<Media, number>();
+
+/** Creates a Media object and initializes private data. */
+export function createMedia(
+    mediaArgs: ConstructorParameters<typeof Media>,
+    mediaMessageCallback: MediaMessageCallback
+) {
+    const media = new Media(...mediaArgs);
+    MediaMessageCallbacks.set(media, mediaMessageCallback);
+    MediaUpdateListeners.set(media, new Set());
+    MediaLastUpdateTimes.set(media, 0);
+
+    return media;
+}
+
 type UpdateListener = (isAlive: boolean) => void;
 
 export default class Media {
     #id = uuid();
 
-    // Timestamp of last status update
-    _lastUpdateTime = 0;
-    _updateListeners = new Set<UpdateListener>();
+    get #updateListeners() {
+        const updateListeners = MediaUpdateListeners.get(this);
+        if (!updateListeners)
+            throw logger.error("Missing media update listeners!");
+        return updateListeners;
+    }
+    get #mediaMessageCallback() {
+        const callback = MediaMessageCallbacks.get(this);
+        if (!callback) throw logger.error("Missing media message callback!");
+        return callback;
+    }
+    get #lastUpdateTime() {
+        const lastUpdateTime = MediaLastUpdateTimes.get(this);
+        if (!lastUpdateTime) throw logger.error("Missing last update time!");
+        return lastUpdateTime;
+    }
 
     activeTrackIds: Nullable<number[]> = null;
     breakStatus?: BreakStatus;
@@ -65,19 +100,13 @@ export default class Media {
     preloadedItemId: Nullable<number> = null;
     queueData?: QueueData;
 
-    constructor(
-        public sessionId: string,
-        public mediaSessionId: number,
-        public _sendMediaMessage: (
-            message: DistributiveOmit<SenderMediaMessage, "requestId">
-        ) => Promise<void>
-    ) {}
+    constructor(public sessionId: string, public mediaSessionId: number) {}
 
     addUpdateListener(listener: UpdateListener) {
-        this._updateListeners.add(listener);
+        this.#updateListeners?.add(listener);
     }
     removeUpdateListener(listener: UpdateListener) {
-        this._updateListeners.delete(listener);
+        this.#updateListeners?.delete(listener);
     }
 
     editTracksInfo(
@@ -85,7 +114,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...editTracksInfoRequest,
             type: "EDIT_TRACKS_INFO",
             mediaSessionId: this.mediaSessionId
@@ -108,7 +137,7 @@ export default class Media {
 
         return getEstimatedTime({
             currentTime: this.breakStatus.currentBreakClipTime,
-            lastUpdateTime: this._lastUpdateTime,
+            lastUpdateTime: this.#lastUpdateTime,
             duration: currentBreakClip.duration
         });
     }
@@ -127,7 +156,7 @@ export default class Media {
 
         return getEstimatedTime({
             currentTime: this.breakStatus.currentBreakTime,
-            lastUpdateTime: this._lastUpdateTime,
+            lastUpdateTime: this.#lastUpdateTime,
             duration: currentBreak.duration
         });
     }
@@ -144,7 +173,7 @@ export default class Media {
         if (this.playerState === PlayerState.PLAYING) {
             return getEstimatedTime({
                 currentTime: this.currentTime,
-                lastUpdateTime: this._lastUpdateTime,
+                lastUpdateTime: this.#lastUpdateTime,
                 duration: this.media?.duration
             });
         }
@@ -161,7 +190,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...getStatusRequest,
             type: "MEDIA_GET_STATUS",
             mediaSessionId: this.mediaSessionId
@@ -175,7 +204,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...pauseRequest,
             type: "PAUSE",
             mediaSessionId: this.mediaSessionId
@@ -189,7 +218,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...playRequest,
             type: "PLAY",
             mediaSessionId: this.mediaSessionId
@@ -203,7 +232,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...new QueueInsertItemsRequest([item]),
             type: "QUEUE_INSERT",
             sessionId: this.sessionId,
@@ -218,7 +247,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...queueInsertItemsRequest,
             type: "QUEUE_INSERT",
             sessionId: this.sessionId,
@@ -237,7 +266,7 @@ export default class Media {
             const jumpRequest = new QueueJumpRequest();
             jumpRequest.currentItemId = itemId;
 
-            this._sendMediaMessage({
+            this.#mediaMessageCallback?.({
                 ...jumpRequest,
                 type: "QUEUE_UPDATE",
                 sessionId: this.sessionId,
@@ -283,7 +312,7 @@ export default class Media {
                 reorderItemsRequest.insertBefore = existingItem.itemId;
             }
 
-            this._sendMediaMessage({
+            this.#mediaMessageCallback?.({
                 ...reorderItemsRequest,
                 type: "QUEUE_REORDER",
                 sessionId: this.sessionId,
@@ -301,7 +330,7 @@ export default class Media {
         const jumpRequest = new QueueJumpRequest();
         jumpRequest.jump = 1;
 
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...jumpRequest,
             type: "QUEUE_UPDATE",
             sessionId: this.sessionId,
@@ -318,7 +347,7 @@ export default class Media {
         const jumpRequest = new QueueJumpRequest();
         jumpRequest.jump = -1;
 
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...jumpRequest,
             type: "QUEUE_UPDATE",
             sessionId: this.sessionId,
@@ -348,7 +377,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...queueRemoveItemsRequest,
 
             mediaSessionId: this.mediaSessionId,
@@ -364,7 +393,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...queueReorderItemsRequest,
 
             mediaSessionId: this.mediaSessionId,
@@ -383,7 +412,7 @@ export default class Media {
         const setPropertiesRequest = new QueueSetPropertiesRequest();
         setPropertiesRequest.repeatMode = repeatMode;
 
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...setPropertiesRequest,
             type: "QUEUE_UPDATE",
             sessionId: this.sessionId,
@@ -398,7 +427,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...queueUpdateItemsRequest,
             type: "QUEUE_UPDATE",
             sessionId: this.sessionId,
@@ -413,7 +442,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...seekRequest,
             type: "SEEK",
             mediaSessionId: this.mediaSessionId
@@ -427,7 +456,7 @@ export default class Media {
         successCallback?: () => void,
         errorCallback?: (err: CastError) => void
     ) {
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...volumeRequest,
             type: "MEDIA_SET_VOLUME",
             mediaSessionId: this.mediaSessionId
@@ -445,7 +474,7 @@ export default class Media {
             stopRequest = new StopRequest();
         }
 
-        this._sendMediaMessage({
+        this.#mediaMessageCallback?.({
             ...stopRequest,
             type: "STOP",
             mediaSessionId: this.mediaSessionId
diff --git a/ext/src/cast/sdk/media/index.ts b/ext/src/cast/sdk/media/index.ts
index f2a0c5a..c584c0a 100644
--- a/ext/src/cast/sdk/media/index.ts
+++ b/ext/src/cast/sdk/media/index.ts
@@ -1,140 +1,20 @@
 "use strict";
 
-import Media from "./Media";
+export * from "./enums";
+export * from "./classes";
 
-import {
-    ContainerType,
-    HdrType,
-    HlsSegmentFormat,
-    HlsVideoSegmentFormat,
-    IdleReason,
-    MediaCommand,
-    MetadataType,
-    PlayerState,
-    QueueType,
-    RepeatMode,
-    ResumeState,
-    StreamType,
-    TextTrackEdgeType,
-    TextTrackFontGenericFamily,
-    TextTrackFontStyle,
-    TextTrackType,
-    TextTrackWindowType,
-    TrackType,
-    UserAction
-} from "./enums";
+export { default as Media } from "./Media";
 
-import {
-    AudiobookChapterMediaMetadata,
-    AudiobookContainerMetadata,
-    Break,
-    BreakClip,
-    BreakStatus,
-    ContainerMetadata,
-    EditTracksInfoRequest,
-    GenericMediaMetadata,
-    GetStatusRequest,
-    LiveSeekableRange,
-    LoadRequest,
-    MediaInfo,
-    MediaMetadata,
-    MovieMediaMetadata,
-    MusicTrackMediaMetadata,
-    PauseRequest,
-    PhotoMediaMetadata,
-    PlayRequest,
-    QueueData,
-    QueueInsertItemsRequest,
-    QueueItem,
-    QueueJumpRequest,
-    QueueLoadRequest,
-    QueueRemoveItemsRequest,
-    QueueReorderItemsRequest,
-    QueueSetPropertiesRequest,
-    QueueUpdateItemsRequest,
-    SeekRequest,
-    StopRequest,
-    TextTrackStyle,
-    Track,
-    TvShowMediaMetadata,
-    UserActionState,
-    VastAdsRequest,
-    VideoInformation,
-    VolumeRequest
-} from "./classes";
+export const DEFAULT_MEDIA_RECEIVER_APP_ID = "CC1AD845";
 
-export default {
-    DEFAULT_MEDIA_RECEIVER_APP_ID: "CC1AD845",
-    timeout: {
-        editTracksInfo: 0,
-        getStatus: 0,
-        load: 0,
-        pause: 0,
-        play: 0,
-        queue: 0,
-        seek: 0,
-        setVolume: 0,
-        stop: 0
-    },
-
-    Media,
-
-    // Enums
-    ContainerType,
-    HdrType,
-    HlsSegmentFormat,
-    HlsVideoSegmentFormat,
-    IdleReason,
-    MediaCommand,
-    MetadataType,
-    PlayerState,
-    QueueType,
-    RepeatMode,
-    ResumeState,
-    StreamType,
-    TextTrackEdgeType,
-    TextTrackFontGenericFamily,
-    TextTrackFontStyle,
-    TextTrackType,
-    TextTrackWindowType,
-    TrackType,
-    UserAction,
-
-    // Classes
-    AudiobookChapterMediaMetadata,
-    AudiobookContainerMetadata,
-    Break,
-    BreakClip,
-    BreakStatus,
-    ContainerMetadata,
-    EditTracksInfoRequest,
-    GenericMediaMetadata,
-    GetStatusRequest,
-    LiveSeekableRange,
-    LoadRequest,
-    MediaInfo,
-    MediaMetadata,
-    MovieMediaMetadata,
-    MusicTrackMediaMetadata,
-    PauseRequest,
-    PhotoMediaMetadata,
-    PlayRequest,
-    QueueData,
-    QueueInsertItemsRequest,
-    QueueItem,
-    QueueJumpRequest,
-    QueueLoadRequest,
-    QueueRemoveItemsRequest,
-    QueueReorderItemsRequest,
-    QueueSetPropertiesRequest,
-    QueueUpdateItemsRequest,
-    SeekRequest,
-    StopRequest,
-    TextTrackStyle,
-    Track,
-    TvShowMediaMetadata,
-    UserActionState,
-    VastAdsRequest,
-    VideoInformation,
-    VolumeRequest
+export const timeout = {
+    editTracksInfo: 0,
+    getStatus: 0,
+    load: 0,
+    pause: 0,
+    play: 0,
+    queue: 0,
+    seek: 0,
+    setVolume: 0,
+    stop: 0
 };
diff --git a/ext/src/cast/senders/media.ts b/ext/src/cast/senders/media.ts
index a11b48a..adba2cd 100644
--- a/ext/src/cast/senders/media.ts
+++ b/ext/src/cast/senders/media.ts
@@ -14,7 +14,7 @@ const logger = new Logger("fx_cast [media sender]");
 interface MediaSenderOpts {
     mediaUrl: string;
     contextTabId?: number;
-    targetElementId?: number;
+    mediaElement?: HTMLMediaElement;
 }
 
 export default class MediaSender {
@@ -23,6 +23,7 @@ export default class MediaSender {
     private mediaUrl: string;
     private contextTabId?: number;
 
+    /** Target media element if loaded as a content script. */
     private mediaElement?: HTMLMediaElement;
 
     private isLocalMedia = false;
@@ -34,12 +35,7 @@ export default class MediaSender {
     constructor(opts: MediaSenderOpts) {
         this.mediaUrl = opts.mediaUrl;
         this.contextTabId = opts.contextTabId;
-
-        if (opts.targetElementId) {
-            this.mediaElement = browser.menus.getTargetElement(
-                opts.targetElementId
-            ) as HTMLMediaElement;
-        }
+        this.mediaElement = opts.mediaElement;
 
         this.init();
     }
@@ -79,7 +75,7 @@ export default class MediaSender {
             ),
             undefined,
             err => {
-                logger.error("Failed to initialize cast API", err);
+                logger.error("Failed to initialize cast SDK", err);
             }
         );
     }
@@ -270,10 +266,21 @@ export default class MediaSender {
     }
 }
 
+/**
+ * If loaded as a content script, opts are stored on the window object.
+ */
 if (window.location.protocol !== "moz-extension:") {
     const window_ = window as any;
+
+    let mediaElement: Optional<HTMLMediaElement>;
+    if (window_.targetElementId) {
+        mediaElement = browser.menus.getTargetElement(
+            window_.targetElementId
+        ) as HTMLMediaElement;
+    }
+
     new MediaSender({
         mediaUrl: window_.mediaUrl,
-        targetElementId: window_.targetElementId
+        mediaElement
     });
 }
diff --git a/ext/src/cast/utils.ts b/ext/src/cast/utils.ts
index fc72e07..5a5987a 100644
--- a/ext/src/cast/utils.ts
+++ b/ext/src/cast/utils.ts
@@ -1,6 +1,8 @@
 import { ReceiverDevice, ReceiverDeviceCapabilities } from "../types";
 import { Receiver } from "./sdk/classes";
 import { Capability, ReceiverType } from "./sdk/enums";
+import { MediaCommand } from "./sdk/media/enums";
+import { _MediaCommand } from "./sdk/types";
 
 /**
  * Check receiver device capabilities bitflags against array of
@@ -29,8 +31,8 @@ export function hasRequiredCapabilities(
     });
 }
 
+/** Convert capabilities bitflags to string array. */
 export function convertCapabilitiesFlags(flags: ReceiverDeviceCapabilities) {
-    // Convert capabilities bitflag to string array
     const capabilities: Capability[] = [];
     if (flags & ReceiverDeviceCapabilities.VIDEO_OUT)
         capabilities.push(Capability.VIDEO_OUT);
@@ -47,6 +49,26 @@ export function convertCapabilitiesFlags(flags: ReceiverDeviceCapabilities) {
     return capabilities;
 }
 
+/** Convert media commands bitflags to string array. */
+export function convertSupportedMediaCommandsFlags(flags: _MediaCommand) {
+    const supportedMediaCommands: string[] = [];
+    if (flags & _MediaCommand.PAUSE) {
+        supportedMediaCommands.push(MediaCommand.PAUSE);
+    } else if (flags & _MediaCommand.SEEK) {
+        supportedMediaCommands.push(MediaCommand.SEEK);
+    } else if (flags & _MediaCommand.STREAM_VOLUME) {
+        supportedMediaCommands.push(MediaCommand.STREAM_VOLUME);
+    } else if (flags & _MediaCommand.STREAM_MUTE) {
+        supportedMediaCommands.push(MediaCommand.STREAM_MUTE);
+    } else if (flags & _MediaCommand.QUEUE_NEXT) {
+        supportedMediaCommands.push("queue_next");
+    } else if (flags & _MediaCommand.QUEUE_PREV) {
+        supportedMediaCommands.push("queue_prev");
+    }
+
+    return supportedMediaCommands;
+}
+
 interface GetEstimatedTimeOpts {
     currentTime: number;
     lastUpdateTime: number;