It seems like PeerTube adoption is slower than Mastodon. Blender's instance[1] is the only other non-toy instance I know of. It's probably because video is much harder to work with, so fewer people do it in the first place. [1] https://video.blender.org/
I see one of two possible interpretations: The first is that given that you choose to upload to both YouTube and a PeerTube instance, no one will watch the PeerTube instance. So PeerTube is just an emergency hedge against something going south on YouTube. Insurance is good, but the premiums in terms of time might be a little high.
The second is that it's possible some of those YouTube people wouldn't watch the videos on PeerTube even if they were removed from YouTube. That's a harder problem to solve.
I guess I don't intend to undermine the nobility of the effort, just a natural skeptic when it comes to the feasibility of it going anywhere.