"worked"
They did a couple of balance tricks where the combination of repetition of the trick plus placebo effect makes it seem like it works, and you call that worked? Find someone who has used it for more than the 3 minute demonstration, who has had it for 6 months and says it works (and isn't getting paid by them). Why is it that the person who is trying to convince you it works is pushing down on the arm instead of handing you an X lb dumbbell? Because with a person doing it he can vary how hard he pushes too. This is basic carnival snake oil sales 101.