o_0
You're asking this, here? Have you read many of the news articles, their comments, and the views expressed within them? This is not the place to come for a random sample on this subject. This is about as biased a source on the matter as they come. Unless that's what you're looking for, in which case whatever you're doing with this data is not true research, but cherry-picking. It's like going to a Democratic party convention and asking if Sarah Palin should be president.
But, for the sake of some discussion, and because I do hold somewhat of a minority opinion on this on these forums, I suppose I'll give my own answers. No, I do not necessarily believe that video games cause more youth violence. It may aggravate pre-existing mental conditions that lead to it, but it's not going to turn an otherwise peaceful kid into the next Columbine shooter. I do believe that overuse of video games can lead to poorer social skills, however, at least if you are playing by yourself or online. WoW and CoD are not the places to turn to hear great examples of how to deal with others. The majority of communication is non-verbal, and if you can't see or at least get some sense of how the other person is reacting to your messages or sending their own, much is lost in translation. And without going out and actually interacting with others face-to-face, those skills can't develop well. However, this can be the same for anyone who over-indulges in activities that can be done by one's self, such as using the internet, watching TV or movies, listening to music, and even reading books. But games do have some qualities that encourage over-use that other media do not have, and in that regard they do stand alone a bit on this. As far as de-sensitization, I am honestly not sure how I feel games impact that. I think that perhaps it might be the same as the answer to games' effect on social skills, that they are one of many different forms of media that can have an impact, but there is the aspect of games being interactive that may also change things. I cannot really say if it really does, but I can imagine there being some potential for it to have at least a little more impact than other media. Anyway, that's what I think. Please take my suggestions above into account when going forward with your research on this data.