PeerTube is a free, decentralized and federated video platform developed as an alternative to other platforms that centralize our data and attention, such as YouTube, Dailymotion or Vimeo. But one organization hosting PeerTube alone may not have enough money to pay for bandwidth and video storage of its servers, all servers of PeerTube are interoperable as a federated network, and non-PeerTube servers can be part of the larger Vidiverse (federated video network) by talking our implementation of ActivityPub. Video load is reduced thanks to P2P in the web browser using WebTorrent or p2p-media-loader.
I want to add that the peer instances should not be confused with the software itself. PeerTube is like Wordpress, it depends where you install it. You have full control over it. The instances are simply people taking this trade-free software and installing on their server. If then they limit users then that’s not PeerTube’s fault :).
It is another one of these decentralized platforms where you can join different servers (instances) and upload your videos. There are no trackers and ads and probably no algorithm that want’s to keep you hooked in the platform like youtube’s algorithm. Mind you, some instances might have a limit as to how much video material you can upload, like only 2 gb per day or 50 gb in total.