The Fediverse has community-owned alternatives to YouTube and Twitch called @peertube and @owncast. If you would like to help them grow, you might want to follow some PeerTube and OwnCast accounts from this curated list:
➡️ https://social.growyourown.services/@FediVideo/113034585910396420
You can follow and interact entirely from Mastodon, you don't need a PeerTube or OwnCast account.
More info about how to follow PeerTube from Mastodon at https://fedi.tips/how-do-i-use-peertube-how-do-i-follow-peertube-accounts-from-mastodon and most of this also applies to following OwnCast accounts.