Peertube is a federated YouTube replacement. You can have it where an instance connects to other instances, and you can also sign up to individual channels using Lemmy so new videos show up on your feed, and you can watch, comment, and upvote and that integrates with the channel. Federated instances can also act as seeds for the other instances so popular videos can be distributed, and viewers seed to other viewers so it a bunch of people are watching a video that takes the load off of the servers. It also has streaming including chat integration.

Another great project in the fediverse.

https://diode.zone/ is one peertube instance.