Personally, I don't understand how PeerTube works. The other day I tried downloading a video using a .torrent client, but I just couldn't do it. There were no seeders, not even the original server, and no peers. And the reason I wanted to do that was to share the burden on the server by seeding the video myself once downloaded. Maybe I was doing something wrong, but if I wasn't and it really doesn't work like that, I fail to see the point of PT, to be honest.
I will try again from a different computer, though, just in case it was my fault.