I don't watch much Let's Play stuff. But every once in a while, I like to read them, especially on games that I've wanted to beat before, and just didn't end up investing the time. Like the aforementioned The 7th Saga. A good Let's Play will possibly clue you in to tricks that you may not have realized, so in some ways, it might be better just for games that you've actually either played or beaten. (There's one on Thousand Arms that is somewhat interesting as well. I've got the game, but I've never really gotten past the first couple of hours.)