User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:80.0) Gecko/20100101 Firefox/80.0

Steps to reproduce:

Enable VAAPI for X11.
Watch a high-resolution video, e.g. 1080p in h264 format (Firefox VAAPI doesn't support vp9 currently). An example video is at https://www.bilibili.com/video/BV1f4411R7yx?p=2 but you need an account to watch 1080p. Or with the enhanced-h264ify extension blocking vp9 videos, you can pick a YouTube video.
Ensure it's using VAAPI by seeing usage data with intel_gpu_top.

Actual results:

Interrupts happen while playing, with the following log:

[Child 53709, MediaDecoderStateMachine #1] WARNING: Decoder=7f8801fb5000 Decode error: NS_ERROR_DOM_MEDIA_DECODE_ERR (0x806e0004) - virtual mozilla::MediaResult mozilla::FFmpegVideoDecoder<58>::DoDecode(mozilla::MediaRawData *, uint8_t *, int, bool *, MediaDataDecoder::DecodedData &): avcodec_send_packet error: -1094995529: file /builds/worker/checkouts/gecko/dom/media/MediaDecoderStateMachine.cpp, line 3470

Expected results:

There should be no interrupts and no such error logs.

My screen is 1920x1080 and video card is Intel Corporation HD Graphics 630.

This doesn't happen with low-resolution videos e.g. 360p or 480p. While I watch YouTube video with enhanced-h264ify the video goes high-resolution for a while and gets an interrupt, YouTube thinks the network isn't serving well and switches to 360p / 480p and it lasts a while until YouTube decides to use higher-resolution videos again. I don't remember if this problem occurs with 720p.

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

(Jan Andre Ikenmeyer [:darkspirit] from bug 1619523 comment #33)

everyone will run into the following regressions, they are probably the same: bug 1645671, bug 1645673, bug 1643855. DMABuf video textures aren't finished yet: bug 1629788 comment 27. These bugs have 3 weeks to be fixed in 79 beta, otherwise they'll hit release and affect Wayland users who have manually enabled VAAPI.