Its closer to a cross between Twitter, Email, and Bittorrent. People create accounts like Email, on the servers they like. You can publish new videos to your followers, like Twitter, using ActivityPub. Followers on other servers are notified via ActivityPub that a new video was made.

When followers click on the video, its shared with Bittorrent over WebRTC over everyone's Web Browser (with the PeerTube server as the permanent seed).

Personally, I don't like the idea of the Bittorrent bit, due to the publishing of IP addresses. But I really like the idea of federated video sharing through ActivityPub.

---------

I guess ActivityPub might be the new RSS, if RSS lists were hosted on servers and had concepts about users. And PeerTube is mostly about notifying ActivityPub members that new videos are available.