After watching the video, I'm going to say that these things are no joke. The skiing in the vid is probably better than what 80% of the people on epicski are capable of, and the vast majority of the general public. This is not a tool for the low intermediate. It it is better suited for a low-advanced skier learning how to edge and carve like an rec-expert. I can easily see how this could be used to get people past the classic plateau in the learning curve.
Obviously you're not going to go extreme skiing with it, or the skis they are mounted on. Or even normal freeskiing, for that matter.