Examples include: Scary Game Squad, Gamegrumps, Team Double Dragon, and the like.
I just find let's plays a lot more entertaining when multiple people are playing and chatting than when it's just one person rambling. But these are weirdly hard to search for!
Not quite the same thing, but one thing I have seen is players that stream slower-paced games chatting with remote viewers.
On Cataclysm: Dark Days Ahead, Vormithrax, is well-known for this, and watching his videos has often been recommended on Reddit as a way to learn the (quite complicated) game, as he tends to walk people through what he's thinking about while playing.
Obviously, that doesn't work with every game genre; they have to be able to field suggestions and questions from viewers while concurrently playing. But for turn-based games, I think that it can work well.