I've done a couple of Youtube play alongs. When recording them I worked harder on getting the song under my fingers than I normally would. I really wanted it to be spot on if it was going to be out there. I liken it to being back at school and having to learn a piece to play to your teacher.
There is a downside. Doing a gig with a guy I know recently, he said "Oh I saw something great on your youtube channel, lets do Knock on wood". I couldn't even remember what key it was in let alone the part I played