I once did a research paper on the video game violence issue. In my opinion, a video game is just as dangerous as the child that precieves it as such. The problem isn't with the game's content, but rather it's the child's mental state. I've been playing Doom for years, but I've also never killed anyone because of it. If a child is already mentally unstable, then yes, I believe that a game like Manhunt could drive that person over the edge, so to speak.
And yet, other mediums go unnoticed. People want violent video games banned, yet that remake of The Texas Chainsaw Massacre is still on Wal-Mart shelves. (I even bought a copy.)
But like the article says, this does all go back to the parents. Sadly, in today's society it is easier to give a kid a video game to make them shut up than it is to actually spend time with that child. And that leads to all the problems in the first place.