Reviews? Of course (if the game is good).
Doing let's plays / walkthrough? No way to prove that, but I higly doubt it.
I don't see how watching a guy play the entire game encourages people to buy the game if they know what's going to happen.
But Games =/= Movies.
Everyone who plays a game is going to have a different experience. Because of what actions or choices they make. Choosing classes, what Pokemon to use, weather to go down this pipe or not, if you should sneak by, or run in and gun down everything, or whatever other choices you might have. A lets player might do it one way, but the viewer would want to do it a different way.
Movies, however, are exactly the same every time. You get the same experience every time.
Also, Lets Plays, IMO are better than Reviews, because you actually see what the game is like. They usually show the straightforward gameplay.
Unlike a review which takes the gameplay, and chops it up into a bunch of short clips so you don't get a feel for what a game is like.
Its really disappointing, because there are some LPers that I would really want to see do some Nintendo games, but they won't because of how Nintendo treats lets plays. :/
[SIZE="1"]Except for the cutscenes, the Subspace Emissary sucked anyway.[/SIZE]