The javascript engine and rendering engines are what are generally affected by being backgrounded. So yes, generally the media library will continue receiving the combined video/audio stream and not bother rendering the video frames
Youtube uses the Media Source Extensions API, which means that JS is responsible for fetching compressed video data and feeding it into the decoder, so it can implement adaptive streaming. Pause JS for more than a few seconds and the video will stop playing.
My understanding is that most video websites like Youtube use Media Source Extensions, a standard which allows javascript to download and assemble video streams in non-standard ways. This work is done by page JS and passed to the browser to decode and render. AFAIK youtube uses this to implement DASH streaming.
Presumably there is no easy way to disable page JS but keep your youtube video downloading.
Chrome does this for a long time now and I don't consider it an issue. You see a frozen version of the last decoded keyframe until the next one is decoded. Elegant solution IMO.
That makes sense, it seems I haven’t looked closely enough to notice.
I couldn’t find info on how often a keyframe is expected from YouTube, but I’m recalling the bad old divx days where you sometimes had a frame per scene and skipping was very slow.
