It’s federated like Lemmy, so each platform has ‘local videos’ and an ‘all videos’ section. E.g. https://fedi.video/videos/local and https://fedi.video/videos/overview
Of course, since it’s federated, it means other platforms like PieFed, MBIN and Mastodon can access the same stuff, so you don’t need to register anywhere if you’re on one of them.
Just a temporary thing with Lemmy I think - PeerTube (like Lemmy and Mastodon) are already part of the fediverse. You used to be able to successfully subscribe to PeerTube channels from Lemmy (when it was on 0.18), and likely will be able to in future (it’s just a Lemmy bug that needs a fix).