That video-games impact children's behavior there's no doubt, it's just like tv. But the extent of that impact on the agressive-behavior aspect?

There's so much controversy, but there seems to indeed be a link between those 2 factors: here's 2 famous meta-analysis (this and this one), one of them with a sample of more than 134000 individuals.

If you'd ask me, I'd say it's not just a matter of increased aggressiveness. For example, there are studies that show that children who view larger doses of sexual content on television have the tendency to engage in sexual behavior earlier and have more sexual partners than children who don't view that type of content. But this could merely be an expression of the knowledge/experience they have, those consequences are not necessarily negative (if they are practicing safe sex or have good principles regarding sexual relationships). Besides, these kind of studies are mostly correlational, and even if the argument of "that's how we do all these type of studies" is brought to the table, it doesn't eliminate the limits of the study itself.