Actually this isn't at all surprising. though that last line about games being useful to test for addiction isn't right
Gaming isn't addictive, (Extra Credits covered this, I'll post a link later.) Addiction refers to altering the brain chemistry, where the brain needs a specific stimuli to function, games have never been shown to do that. Games are compelling, they have a strong appeal to them.
The study in Belgium has confirmed that when playing games you gain a sense of control,your actions control your fate. In games the outcome of your actions is almost immediate, so you get immediate reward for success, and in most games a tiny mistake can be easily shaken off.
The problem with Game Compulsion, (Here I'm referring it to teens and young adults) is what it really means.
Here's the truth, i play games, read books spend time on the net, it's escapism, and the truth is the reason I'm so determined to to all this is in my real life, I feel kinda trapped, I think only a handful of people give a damn, and I have this gnawing feeling that I won't graduate, not because 'm not smart but because I forgot to do some grad requirement. SO the truth is, I don't play games because I'm addicted, I play games because I want to be somewhere where I'm in control.
but I'm getting ranty so I'm going to stop now.
oh like I promised, if this game addiction thing was ineresting to you Extra Credits Did an episode on it at Penny Arcade
http://penny-arcade.com/patv/episode/game-addiction-pt.1