What exactly are they? Coach B's website has a short description yet I can't get exactly how they are performed and what counts as one rep (floor-below the knee-hang = one rep or each of those is a rep)?
The other deal is that the 3 positions can be whatever you want them to be, really. The point is to make the exercise suitable for the athlete in question.
Typically you'd start from the floor, then from the hang/knees, then from the high hang. But if you have an athlete who's snatch is great from the hang for reasons of positioning, and then sucks from the floor, it can help to start at the top and work down to get the lifter into the proper positions and gradually add a little more ROM to each lift.