I read many comments on how PeerTube isn’t sustainable as a YouTube alternative and, while it’s certainly true right now, are we sure it will be the same in the near future?
The platform is growing and the new mobile app is making great progress; I can certainly see some people investing in a major instance some day, accelerating the platform adoption.
If multiple people are watching the same video, at the same resolution, it uses WebRTC (HLS P2P) to share data between them, saving bandwidth from the PeerTube instance.
A PeerTube instance can also function as a peer (seed) for another PeerTube instance.