A person can use a video game to vent and remove their violent tendencies. A person can play Grand Theft Auto or Halo or a fighting game and use that as a medium in the same sort of sense of punching a wall or screaming into a pillow. It's better to shoot at polyons than at real people. It's for the truly unbalanced people that cannot distinguish between reality and fiction that we should worry about. It's a parent's duty to reinforce that fact to their children; that it is all fun and games and none of it is real. It's like how children imitate Superman and jump off from roofs, believing that they too can fly. Same sense. Different situation.