Install mpv and yt-dlp.
Use play-with addon to open youtube or other video links directly in mpv.
Periodically convert youtube subscriptions into OPML using an userscript.
Import OPML into freetube or other RSS reader to check for new videos.
https://addons.mozilla.org/en-US/firefox/addon/play-with/
https://github.com/theborg3of5/Userscripts/tree/master/youtu...