Video games teach people to deal with frustrations in the wrong way.  In dealing with frustrations and aggression by using video games as an outlet, players of these games often assume that the problem is gone or dealt with.  This is often not the case, with many sources of frustration being ones which repeat day in and day out.  Given that this is the case, video games prevent people from dealing with the root causes of their problems and thus leave people more susceptible to frustration in the future.  Further, playing back into the first point on proposition, they teach players only one method of dealing with their problems, which is resorting to violence, so should they seek to deal with their frustrations in the real world, often the solutions they do engage with are ones which are suboptimal.