You can probably implement a dumb version of this where transcode a few different versions with ffmpeg (which is amazing, but takes some tinkering), use browser

You can probably implement a dumb version of this where transcode a few different versions with ffmpeg (which is amazing, but takes some tinkering), use browser API's to guess the right one as a default, and give the user control if they'd like to switch. I'd still try HLS but this may be good enough for v1, depending on what you're building.