Personally, I take one experience in college as proof enough that Violence in video games may incidentally translate to some real world violence.
The story: I was playing marathon sessions of Need for Speed: Most Wanted, and during my playtime, pretty much any time I saw a cop car my instinct was to RAM THE SHIT out of it. One night, me and buddies had decided to go get pizza at Little Caesars and I pull up to a stop and see a cop car crossing my path. Without thinking, I put my foot on the gas and start to accellerate before I realize that YES, smashing cop cars is BAD and hit the brakes again.
Realisticly, it translated to about as much as me stopping, jerking forward a little bit and stopping again. No harm done, but it scared the shit out of me that I had allowed my driving in game to effect me out of game. Since then, I have ALWAYS tried harder to make the distinction.