In general, I watch the combine for O line ... I mean I dig the other stuff, but I get the most from watching them in comparison to other positions, because their movements are usually hidden, and watching them do the same drill person after person comparing them in real time I get a good sense of coordination and movement skills that I can only guess at on tape. THat's me, some are better at that.
I rarely need to see the same with DBs because they usually separate themselves with their play on tape. But ... this class is so good top to bottom that in order to differentiate and get them in order I actually need all the drills as well as timed speeds (specifically 3 cone and short shuttle).