I would have quit to save him the trouble of the decision. Developers should be judged on more than an incident like this. If the developer is as productive or more productive than the others, does it really matter if you catch him / her watching a movie sometimes?

Yeah, it really does. Not only is this sort of behavior miserably unprofessional it corrodes morale around the office when everyone who isn't a developer catches wind that the prima donnas in IT are sitting around playing video games and watching movies while everyone else is busting their ass.

Well, then, I would blame the non-ITs (managers) for a bad organizational model where they don't have enough work for their IT department.

I have a sense that this might hold true for more non-development IT roles as it is very rare for actual developers to sit around watch movies doing nothing unless they're truly in need of a break. Engineers love to code...or the good ones do.

Personally, I can't concentrate on doing development for eight straight hours. My focus doesn't fit in a neat box like that. Some days I'm burnt at four hours (but I might have had superhuman output during that time) and other days I can do marathons of crazy focus for longer than eight hours.