My fear would be that an average Joe would think that it's okay to do that exercise to teach his horse where its feet are - or that Pro Choice boots have something to do with the safety of doing that exercise.
TRD - I agree that he's a trainer that likely knows his horses better than most of the horse-owning population, but I am still surprised at the video. To me it looks like a dangerous exercise for the average horse/rider combo.
Ckayser - that's my worry as well. In all my life I have never encountered a situation where I would need that particular skill. It unnerves me that the panel moves around when the horse touches it; for most "regular" horses, this would be a disaster waiting to happen.