First off, there is a lot of violence in video games, more and more as the gaming industry expands.
Secondly, movies SHOULD NOT be looked at before video games. One fact being in video games you are actually there, the first person view, YOU are the one shooting people in the head, YOU are the one trying to disarm a bomb before it kills you. In a movie, you are simply watching it. Now in NO WAY am I saying movies aren't violent, because they by far are the most violent, but your point is not valid.
Also, it is NOT up to the parents to buy the games. An 8 year old kid could easily rent or buy a rated M video game. At least you'd need to show an ID for a R rated movie.
I won't say the games aren't entertaining, because I love to play them as well. What I will say is how more and more realistic each day games become. Soon you'll have a game that looks identical to real life where you are shooting cops and jacking cars. Especially when young kids play those games, what kind of messages is it really giving them? Bad ones. I don't care if you say it doesn't affect you, because IT DOES, quite a bit. People who play violent video games and get into them have a tendency to be a lot more aggressive than people who don't.
All and all, I think it is something that should be watched, and at the moment, it might be ok, but it's on a close line.