Check out the LBRY protocol and the LBRY desktop app or it's centralized frontend Odysee

LBRY desktop is also centralized btw. AFAIK there are no front ends built by totally different teams from LBRY, although there could be.

I might be inferring the wrong thing from what you're saying, but I believe you're wrong.

The same video that is uploaded on multiple instances can share peers, so when you're watching it, you get it in a decentralized fashion.

Also videos are regular webtorrents, they can be downloaded (or watched) without any support from the instance, as long as one peer is online. Less sure about video description and comments (though comments received by your instance should be displayed).