I am not going to question the findings of the above-mentioned study, as I am sure videogames have negative aspects just as well as positive aspects; instead I am going to post a list of links to articles that investigate the positive effects of videogames. Just to give some perspective:

How do video games affect child health? By fueling violence, shrinking attention, promoting obesity and dulling interest in academic pursuits, if their critics are to be believed. But some physicians, psychiatrists and public health experts see a more positive side: They're betting electronic games can be adapted as tools to ease medical treatments, improve patient outcomes and boost fitness and knowledge for users young and old.
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When stroke victims played virtual reality games in which they imagined they were diving with sharks or snowboarding down a narrow slope, their ability to walk eventually improved, researchers reported in a small study.
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Rosser looks like a football player and cracks jokes like a comic, but his job as a top surgeon and director of the Advanced Medical Technologies Institute at Beth Israel Medical Center in New York is to find better ways to practice medicine. At the top of his list -- video games.
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Playing virtual reality computer games may help treat the condition known as amblyopia, or lazy eye, say researchers.
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Via Opposable Thumbs