Agreed - that UTD video is not a good example of how to do it. For all that the finger gets pointed to PADI, that is shocking for a body that promoted "doing it right".That UTD video is eye opening. Hand on the ground to maintain buoyancy (0:39) kneeling on the bottom (throughout).
There really is no reason why students should be taught anything kneeling other than it might make life slightly easier for the instructor right at the beginning but he will then have to correct the faults that this teaching technique creates.