A question about form: in the video of the hang clean, and (to a lesser extent) the Clean the model doesn't reach full depth until after she catches the bar. In the Power Clean, she squats only enough to catch the bar, and then starts driving up again. This latter seems more efficient and effective to me. Am I picking?
Your observation is correct, doc, it's because the weight used for the hang and full clean is too light for her. When the weight gets lighter and lighter, it's become harder to apply the appropriate force against the bar to do the full lifts (in this case a clean). Afterall, the reason a lifter changes direction is because he/she can't pull the bar high enough to shoulder height. In this case, she pulled the relatively light weight too high and received it in a high position but she had to came down to demonstrate the bottom position.
To some extent, doing a fast full snatch with light weight is easier because you always hold the bar so when you pull it too high you can bring/pull it down with you how quick you want it to be. Now the clean is harder to do because you need to release the grip at the moment you change position. If you pull too high and get down to the bottom in full speed, the bar/weight will come down crashing on you.