This has no relevance to sleep. Bright light supresses melatonin, which is what makes you feel tired. Melatonin levels start to rise around 9 p.m., so if your eyes are 1 or 2 feet from you're monitor at this point, you will reduce the increase of this pro-sleep hormone. Being in front of a computer in a darkened room is very bad (so says my psychiatrist). Also, using the computer or watching TV in bed is also bad for sleep because you're place of sleep should be a place of relaxation, not one of activity which is suppressing you're melatonin seconds earlier. Watching TV (in a different room) is fine because of the inverse square function, which dictates that less light gets to your eyes as you are further away from a screen. So this study means nothing. If they read a book under an incandescent lightbulb in a different room before going to bed, it would be MUCH better than March of the Penguins. It also doesn't say when they went to bed. Melatonin levels peak at 11 p.m.
As for gaming not being bad for sleeping, if you are gaming in front of a computer after 9 p.m., it is.