Okay, that's something which I would say is very convincing.
The comparison to gaming to gambling really caught my attention, because 15% of children acting like an addiction makes for some very undesirable consequences. It may not exactly be violence, but lower grades, less social activities, and other things that come from losing hours a day playing. That is reason enough to think it's bad for children to have unrestricted limits to how much they can play.
Video games are bad because they are addicting enough to draw people's attention from real life. You can't really dictate people to act or not to, but parents should take more of an active role to reduce how much their children play, such as incentives. If their child doesn't make at least a C, they would take away the game until they improve their grade. That would not exactly stop their addiction, but it would be something that parents can do to make it harder for their kids to play all the time and kill their grades.
Gaming is addicting like gambling, but there are many more kids who game that it's worrisome. I can't point to games, but I do know that the average grade in my high school has diminished with each year over the last five or six classes. That's not a clear answer that it's video games, but I really can't think of much else that could cause such a drop in grades. I have considered the other possible causes as well, but the average number of hours they work, social status, and teacher resources have all been about the same. The majority of the failed students had x-boxes and playstations. Many who graduated also did, and many females who failed didn't. This is only anecdotal evidence.