Video games do not make people violent - and based on my observation of at least several thousand peers - it actually has the opposite effect. The truth is video games are a healthy outlet, as well as self train an individual to deal with defeat over and over and over again.
I bet if you took groups of individuals whom played sports for X hours a week, and compared them to an equivalent number of individuals whom played video games for X hours a week, the sports group would have more violent tendencies. This isn't just hyperbola, after observing as many humans as we have in both these activities, it's practically self evident.