--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -560,17 +560,16 @@ MediaDecoder::OnDecoderDoctorEvent(Decod
   DecoderDoctorDiagnostics diags;
   diags.StoreEvent(doc, aEvent, __func__);
 }
 
 void
 MediaDecoder::FinishShutdown()
 {
   MOZ_ASSERT(NS_IsMainThread());
-  mDecoderStateMachine->BreakCycles();
   SetStateMachine(nullptr);
   mVideoFrameContainer = nullptr;
   MediaShutdownManager::Instance().Unregister(this);
 }
 
 nsresult
 MediaDecoder::InitializeStateMachine()
 {
@@ -804,19 +803,19 @@ void
 MediaDecoder::FirstFrameLoaded(nsAutoPtr<MediaInfo> aInfo,
                                MediaDecoderEventVisibility aEventVisibility)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_DIAGNOSTIC_ASSERT(!IsShutdown());
   AbstractThread::AutoEnter context(AbstractMainThread());
 
   LOG("FirstFrameLoaded, channels=%u rate=%u hasAudio=%d hasVideo=%d "
-      "mPlayState=%s",
+      "mPlayState=%s transportSeekable=%d",
       aInfo->mAudio.mChannels, aInfo->mAudio.mRate, aInfo->HasAudio(),
-      aInfo->HasVideo(), PlayStateStr());
+      aInfo->HasVideo(), PlayStateStr(), GetResource()->IsTransportSeekable());
 
   mInfo = aInfo.forget();
 
   Invalidate();
 
   // The element can run javascript via events
   // before reaching here, so only change the
   // state if we're still set to the original

--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -252,17 +252,16 @@ protected:
   {
     Observable,
     Suppressed
   };
 
   using Master = MediaDecoderStateMachine;
   explicit StateObject(Master* aPtr) : mMaster(aPtr) { }
   TaskQueue* OwnerThread() const { return mMaster->mTaskQueue; }
-  MediaResource* Resource() const { return mMaster->mResource; }
   ReaderProxy* Reader() const { return mMaster->mReader; }
   const MediaInfo& Info() const { return mMaster->Info(); }
   MediaQueue<AudioData>& AudioQueue() const { return mMaster->mAudioQueue; }
   MediaQueue<VideoData>& VideoQueue() const { return mMaster->mVideoQueue; }
 
   template <class S, typename... Args, size_t... Indexes>
   auto
   CallEnterMemberFunction(S* aS,
@@ -2681,17 +2680,16 @@ MediaDecoderStateMachine::MediaDecoderSt
   mPlaybackRate(1.0),
   mAmpleAudioThreshold(detail::AMPLE_AUDIO_THRESHOLD),
   mAudioCaptured(false),
   mMinimizePreroll(aDecoder->GetMinimizePreroll()),
   mSentFirstFrameLoadedEvent(false),
   mVideoDecodeSuspended(false),
   mVideoDecodeSuspendTimer(mTaskQueue),
   mOutputStreamManager(new OutputStreamManager()),
-  mResource(aDecoder->GetResource()),
   mVideoDecodeMode(VideoDecodeMode::Normal),
   mIsMSE(aDecoder->IsMSE()),
   INIT_MIRROR(mBuffered, TimeIntervals()),
   INIT_MIRROR(mPlayState, MediaDecoder::PLAY_STATE_LOADING),
   INIT_MIRROR(mVolume, 1.0),
   INIT_MIRROR(mPreservesPitch, true),
   INIT_MIRROR(mLooping, false),
   INIT_MIRROR(mSameOriginMedia, false),
@@ -3449,20 +3447,18 @@ void
 MediaDecoderStateMachine::FinishDecodeFirstFrame()
 {
   MOZ_ASSERT(OnTaskQueue());
   MOZ_ASSERT(!mSentFirstFrameLoadedEvent);
   LOG("FinishDecodeFirstFrame");
 
   mMediaSink->Redraw(Info().mVideo);
 
-  LOG("Media duration %" PRId64 ", "
-      "transportSeekable=%d, mediaSeekable=%d",
-      Duration().ToMicroseconds(), mResource->IsTransportSeekable(),
-      mMediaSeekable);
+  LOG("Media duration %" PRId64 ", mediaSeekable=%d",
+      Duration().ToMicroseconds(), mMediaSeekable);
 
   // Get potentially updated metadata
   mReader->ReadUpdatedMetadata(mInfo.ptr());
 
   EnqueueFirstFrameLoadedEvent();
 }
 
 RefPtr<ShutdownPromise>

--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -225,22 +225,16 @@ public:
     nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction(
       "MediaDecoderStateMachine::DispatchIsLiveStream",
       [self, aIsLiveStream]() {
         self->mIsLiveStream = aIsLiveStream;
       });
     OwnerThread()->DispatchStateChange(r.forget());
   }
 
-  // Drop reference to mResource. Only called during shutdown dance.
-  void BreakCycles() {
-    MOZ_ASSERT(NS_IsMainThread());
-    mResource = nullptr;
-  }
-
   TimedMetadataEventSource& TimedMetadataEvent() {
     return mMetadataManager.TimedMetadataEvent();
   }
 
   MediaEventSource<void>& OnMediaNotSeekable() const;
 
   MediaEventSourceExc<UniquePtr<MediaInfo>,
                       UniquePtr<MetadataTags>,
@@ -641,19 +635,16 @@ private:
   bool mMediaSeekableOnlyInBufferedRanges = false;
 
   // Track enabling video decode suspension via timer
   DelayedScheduler mVideoDecodeSuspendTimer;
 
   // Data about MediaStreams that are being fed by the decoder.
   const RefPtr<OutputStreamManager> mOutputStreamManager;
 
-  // Media data resource from the decoder.
-  RefPtr<MediaResource> mResource;
-
   // Track the current video decode mode.
   VideoDecodeMode mVideoDecodeMode;
 
   // Track the complete & error for audio/video separately
   MozPromiseRequestHolder<GenericPromise> mMediaSinkAudioPromise;
   MozPromiseRequestHolder<GenericPromise> mMediaSinkVideoPromise;
 
   MediaEventListener mAudioQueueListener;