Sepia Search is something that's also build into PeerTube, if the admin have enabled Global Search. Sepia Search uses this list of instances: https://instances.joinpeertube.org/instances
The same can be enabled in PeerTube. You can see here, that I have it enabled on my instance:
I would not recommend using tilvids.com. They do not federate with anyone and do not have global search enabled, which means search only shows videos from tilvids.com. It is however, possible to follow channels from tilvids.com from other platforms (instances).
Simply copy the link from tilvids.com and paste it into the search bar of an instance that has global search enabled.
Platforms can also follow channels directly from tilvids and the videos will show up on said platform.
Discoverability can be a bit finicky on PeerTube. Especially if you don't know how to fine tune the filters.
There really isn't any other big content creators on PeerTube, other than The Linux Experiment, but if you wanna see your favorite creator on PeerTube, ask them.
If you are looking for a platform (instance) to register on, I recommend looking at this list: https://lemmy.wtf/post/15816115
Sort by "hot". And also, check this list out for content: https://lemmy.wtf/post/15810205
Also also, you can still follow channels on tilvids.com, from your own instance, by following the channel's handle.