I do not wish to make you seem loke an idiot, but are you sure you're looking at content from all instances? A lot of instances default to the local content page (home or such), and I find it quite difficult to find all content.

All peertube instances can federate content from other peertube instances, but by default, they only automatically federate content from a list the admin has whitelisted.

However, that's where sepia search comes in to it. Most piefed instances have a search option that lets you use sepia search, and if you do, it will search for content across all peertube instances, and then federate it to your instance so you can watch it

Not exactly what you are looking for but: https://piefed.social/f/fediversevideos has a LOT of channels and communities (like our sister community at !peertube@lemmy.wtf). If your on piefed, you can subscribe to the feed.

https://peertube.wtf has quite a few instances but it can be a bit on the slow side. peertube has issues with a lot of federation once the servers get 1000+ sources. The videos are fine, its just finding the videos that continues to be the issues.