I watch a lot of youtube content, more often then not I'll put on a lets play of a game I'm playing while I'm playing it seeing their takes or how they might be doing things differently, usually that's more for games with replayability, and especially if I can learn more about the game from them off hand. I very rarely watch twitch just because I don't have much interest in being involved with the chat aspect and the constant callouts for donations and subscriptions get grating sooner rather than later.
I did youtube for a few months years back now, right around the time the 10 minute video limit was raised. I had well over 100 videos of Diablo 2 LOD, Age of Empires 2, and I feel like there were a few others. I never managed to finish any of the games and due to being young and still living at home, dealing with school, and parents and their crusade against my gaming time, I fell off and haven't been able to try again since due to my now shitty internet. Its something I've always liked the idea of doing, and doing youtube that short period that I did, really helped boost my confidence with speaking and my ability to speak fluently, going into my senior year of high school this was great for a lot of the presentation projects that came with that.
I watch anything from traditional lets plays, to review content, to the much longer form discussion videos, retrospectives, or more academic approaches to game and gaming culture reviews. Pretty much anything gaming that isn't a squeaky high octane and high energy 15 year old, or adult emulating a 15 year old, I will at least check it out.