there has been a review where they throw the nano around and even out a car with it still working. The screen may get scratched up but just get a case to remedy that. It is a flash player so you don't mess up the hard drive if you drop it or run with it.
also, the 5G ipod only gets about 2hours of video playback time. Music lasts for a lot longer. If you are in the market for a video player, you might want to wait for the new ipod. Touchscreen and a dedicated video player (unlike 5G ipod with video capabilities, notice how the official name is not ipod video, 2hours is only good for an episode or two).