I also want to drop Grayjay in here.
It supports YouTube and can also be used to view other platforms like Twitch, Odysee, PeerTube, etc.
It uses plugins, so you can develop a plugin for the video platform you want to be able to use in Grayjay.
Grayjay also has this Polycentric "decentralized" database so that you can comment and like the videos in those aforementioned platforms.
It's good and everything (although it was a bit rough around the edges here and there), but is a no-go for me personally, unless they've changed their license. When I last checked it wad not open source, but merely source available since the license basically said you're not allowed to modify the source code period. AGPL would've been a far better choice
Totally understandable. I mean, it's still in alpha and yes I do encounter bugs sometimes. I honestly just use it because I can have my feed in grayjay as well.