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.
Yes. You can mirror videos from other instances. This also work as a kind of redundancy, if the PeerTube instance with the original video is down.