There is a decentralized YouTube alternative.
Video hosting is notoriously expensive. PeerTube circumvents this problem, because videos aren't stored on some single server, which would cause high bandwidth cost for the server operator, but largely by the users after they watched them, similar to BitTorrent. This way, the cost of video hosting is distributed among the clients, by using their internet connectivity for sharing.
I believe that PeerTube is an interesting project, and I'd ask you to check it out. It's cool.
Similar to Lemmy, it's not a single running server, but rather a software that can be used to set up a server. So there's many instances. I'm still exploring which instances are interesting. If you have any recommendations, I'd like to hear them.
Theres this old experimental tool called ZeroNet, and it had some really good ways of managing shared data. You could pin websites and files for other people to access, set limits, bandwidth, etc. It'd be nice to have something similar on peertube, like supporting certain creators by immediately hosting their videos for them. Maybe, for example, hosting their latest three videos.