No, it’s like Lemmy, you sign up to an instance and can post on it, and your channel is visible on the whole federated network.

And if PeerTube grows, the “Peer” aspect will be very significant. Basically it’s a torrent and the instance is always seeding, and while other users are watching, you will be sending them data and recieving data from them, lightening load on the instance. It’s a simple and clever system. You can turn the torrent feature off in case you need to hide your IP address.