Just some time ago, I was thinking about some P2P Video service, where everyone would provide the data they have - so like a BitTorrent YouTube

It's called PeerTube. It uses activitypub, the same federation protocol as lemmy. Large creators could certainly afford to host their own videos. Some federation/self-hosting/free software creators already do. Can we have large free-to-use instances where individuals can upload their videos, like we do with Lemmy? I would like to hope so.

But just standing up and copying all of youtube's content? Like I said, it's a MONUMENTAL task. There are around 14e9 videos on there. That's almost two videos for every person on planet earth. And I'm not even sure how useful mirroring would be. It's important for archival purposes, sure, but it's not forward-thinking. For a lot of pieces of content, the value comes mainly from the community surrounding it, not the content itself. Mirroring cuts the community out of the content. I believe that If archiving/mirroring efforts are to succeed at anything beyond occupying disk space, they must be focused on a specific type of content, and headed by people who are genuinely passionate about the content they are archiving, not disintrested data hoarders.