For FFmpegDemuxer we do already drop packets for disabled streams (see https://cs.chromium.org/chromium/src/media/filters/ffmpeg_demuxer.cc?rcl=0&l=1754).
For MSE the application is in control of buffering, so we can't prevent video data from being downloaded and appended to MSE SourceBuffer. AFAIR we are not dropping data from disabled ChunkDemuxerStreams for now - we could look into  that.

Hm, IIRC Dale actually told me ChunkDemuxerStream should be fine and I should look into FFmpeg :)

IIRC for MSE (that's what ChunkDemuxer is for), Chrome has a limit on how much the site can append. Site has to discard the chunks that are no longer needed (e.g. the chunks defining the frames before the current position). I wondered if Chrome tries to do that automatically in common cases and if not, why? Also, if we can still do that with the decoder being disabled (relying on audio frame timestamps?).

Ah this is fixed then! Thanks servolk@. I couldn't remember and didn't have time to check the video code.

MSE has strict rules about buffered data, so we can't do much about that yet.

Sorry for the noise!