I think there are a couple weaknesses in their argument. The difficulty in making studies like this is that you have to make a lot of assumptions in order for the results of the study to hold. Since the research data made use of a natural experiment in which they measure how much extra leisure time was spent on playing video games, it is quite possible young men just found the activity to be more enjoyable compared to socializing and watching television. This by itself does not mean that they are choosing to play video games instead of working.