One problem the D80 occasionally has is that the memory card slot goes bad from use. It's a fairly pricey fix if the camera is out of warranty, so you might ask your friend if he has experienced any corrupt or missing data.

$600 used sounds reasonable with two lenses, but of course it all depends on what kind of glass is included. If they're both Nikon lenses, your probably in good shape.

EDIT: I'm sure you know the D80 doesn't shoot video, it's the D90 that does.