I just found these clips on youtube…

A couple of things I noticed, one is the flare on the camera lens when he breaks a beam. This manifests itself as a vertical broken line – due to the pulsed or scanning nature of the harp.

Another thing is he sometimes seems to hesitate before selecting a note. Playing a laser harp up close can often be visually disorienting – a couple of times I found that I had to count along from the end to make sure that the beam I was about to break really was the one I wanted…

Oh yes and the neat open/close effect when going from 9 beams to 7. Maybe this is when he presses the transpose footswitch?

I think that the fact he loses his place during the performance shows that it really does work – and how difficult it can be to keep track of where you are…