I started firefox in safe mode. Same problem. For more details, Firefox keeps on youtube video in buffering mode, stops to play video, and even doesn't let me click on the video, seems like it freezes. I see this problem in other videos, not only in youtube. Refreshing solves the problem:
firefox -safe-mode
[Child 4952, MediaPlayback #10] WARNING: Decoder=7f8158565c40 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #10] WARNING: Decoder=7f8158565c40 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #11] WARNING: Decoder=7f8158565c40 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #10] WARNING: Decoder=7f8158565c40 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #11] WARNING: Decoder=7f8158565c40 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #4] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #1] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #3] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #3] WARNING: Decoder=7f81529fcb60 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
###!!! [Parent][DispatchAsyncMessage] Error: PClientSourceOp::Msg___delete__ Route error: message sent to unknown actor ID
[Child 4952, MediaPlayback #1] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #1] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #1] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #3] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #3] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #3] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f815057a200 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #1] WARNING: Decoder=7f81503c67a0 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #1] WARNING: Decoder=7f81503c67a0 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
[Child 4952, MediaPlayback #2] WARNING: Decoder=7f81503c67a0 Decode error: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005) - RefPtr<mozilla::MozPromise<RefPtr<mozilla::MediaTrackDemuxer::SamplesHolder>, mozilla::MediaResult, true> > mozilla::MediaSourceTrackDemuxer::DoGetSamples(int32_t): manager is detached.: file /build/firefox/src/mozilla-unified/dom/media/MediaDecoderStateMachine.cpp, line 3411
###!!! [Parent][DispatchAsyncMessage] Error: PClientSourceOp::Msg___delete__ Route error: message sent to unknown actor ID
###!!! [Parent][DispatchAsyncMessage] Error: PClientSourceOp::Msg___delete__ Route error: message sent to unknown actor ID
###!!! [Parent][DispatchAsyncMessage] Error: PClientSourceOp::Msg___delete__ Route error: message sent to unknown actor ID