Why not something open source like PeerTube or even Odysee/LBRY. Alot of (these) channels used to sync to Odysee until that feature got killed on YouTube's side. PeerTube should have a feature to import from YouTube given that your instance has enabled it.
peertube.wtf - heavily federated big instance, enables importing from YouTube video.4d2.org - heavily federated smaller instance ran by 4d2.org, doesn't enable importing from YouTube
poast.tv - "Darkfedi/fediblock" instance, heavily federated with alot of those being instances other instances wouldn't interact with. seriesoftubes has archived alot of content from YouTube that you'd probably like.
peertube.nadeko.net - ran by the same guy as inv.nadeko.net, has content archived from YouTube, not federated with alot of instances, allows importing from YouTube
videos.icum.to - Ashley Jones's instance focused on OC content, doesn't contain videos from other instances, followed by a rough dozen instances including poast.tv, 4d2.org and peertube.nadeko.net
tube.kansanvalta.org - Fnnish instance, conspiracy schizos and their reuploads, doesn't federate
https://player.ojamajo.moe/ - Contains Ojamajo Doremi, Yume no Crayon and Ashita no Nadja in multiple languages, doesn't federate.
810video.com - Japanese instance, sort of like Nico Nico douga. Comedic MADs of gay porn(sort of like GachiMuchi, some people will also upload the full adult videos), TV shows, Japanese "lolcows", anime etc... Also there's some Touhou of course. Federation seems broken, some instance claim to federate but aren't up to date.
Note: There are alot of instances outside of those but you can federate with the most of them with those(outside instances that don't federate, that I don't know/care for)
PeerTube should have a feature to import from YouTube given that your instance has enabled it.
peertube.wtf - heavily federated big instance, enables importing from YouTube
video.4d2.org - heavily federated smaller instance ran by 4d2.org, doesn't enable importing from YouTube
poast.tv - "Darkfedi/fediblock" instance, heavily federated with alot of those being instances other instances wouldn't interact with. seriesoftubes has archived alot of content from YouTube that you'd probably like.
peertube.nadeko.net - ran by the same guy as inv.nadeko.net, has content archived from YouTube, not federated with alot of instances, allows importing from YouTube
videos.icum.to - Ashley Jones's instance focused on OC content, doesn't contain videos from other instances, followed by a rough dozen instances including poast.tv, 4d2.org and peertube.nadeko.net
tube.kansanvalta.org - Fnnish instance, conspiracy schizos and their reuploads, doesn't federate
https://player.ojamajo.moe/ - Contains Ojamajo Doremi, Yume no Crayon and Ashita no Nadja in multiple languages, doesn't federate.
810video.com - Japanese instance, sort of like Nico Nico douga. Comedic MADs of gay porn(sort of like GachiMuchi, some people will also upload the full adult videos), TV shows, Japanese "lolcows", anime etc... Also there's some Touhou of course. Federation seems broken, some instance claim to federate but aren't up to date.
Note: There are alot of instances outside of those but you can federate with the most of them with those(outside instances that don't federate, that I don't know/care for)