I think maybe there is some discussion to be had about the difference between personal violence, such as a particular person carrying out a violent crime, and the general acceptance of violence as a viable solution to a myriad of problems.
I both do not know any violent criminals personally, and have witnessed a rather staggering amount of acceptance of violence in our culture.
I’m reminded here of when the director of communications at Lockheed Martin responded with the following when asked about a possible connection between Columbine and the manufacturing of Triton missiles just down the street (Lockheed being a major employer of many parents in the area):
“I guess I don't see that specific connection because the missiles that you're talking about were built and designed to defend us from somebody else who would be aggressors against us.”
We also accept violence in the criminal justice system even to stop non-violent crimes. We also support wars, see it’s approval rating of post 9-11. I’ve had many a person tell me the solution to some Perceived racial problem was to “wipe them out” and only one of them physically assaulted me.
So it seems to me that we are okay with violence but often do not like carrying it out ourselves in personal disputes. Yet this may only be detoured but the treat of violence being carried out on us if we were to. Unless of course we are in the military and have been told/trained to carry out violent activities with impunity. All in all I am not convinced we are a peaceful nonviolent civilization, quite the opposite. Nor am I convinced that seeing accepted violence everyday on your T.V. Screen, be it video game or otherwise, does not affect this pervasive psychological mindset, agin the opposite.