Yes, it does affect behavior. Whenever I play League of Legends and things aren't going my way or I'm not doing really good I will rage and end up being really angry. Like last night when I was playing my mouse wasn't even working and I pratically couldn't do anything and I was playing with lvl 20 players and I'm only 11 on League and I suck.
Affecting your brain and influencing behavior are two different things. So yes it does affect your brain, influencing behavior depends on the mind of the individual.
Every form of media causes psychological "shuffles".
Whether it be music, games or movies; they induce changes of some sort, to whatever extent. Whether they're good or bad is of no matter at this level, they're changes nonetheless.
i played a shitton of pacman when i was a kid, and it never affected my life.
i'm just your ordinary overweight guy who likes to eat and is escaping from the ghosts of his past. OMG I'M PACMAN.
video games are the side effect, not the cause. an angry person will play violent games because he is angry, a bully will troll online because he is a bully, and people get addicted to mmos and candy crush because they have an addictive behaviour. if you take video games away, you are still left with a violent person,a bully, and an addict.