Oh, and one more example of an instance on the Fediverse you will see frequently on Stacker News: BitcoinTV!

BitcoinTV is a Peertube host that serves videos:

And because Peertube is a federated resource, you can follow any channel on BitcoinTV. For instance, on Mastodon follow @simply_bitcoin@bitcointv.com so that when they post a new episode in their channel, you will see it in your Mastodon account's timeline -- even though you don't have an account on BitcoinTV.