Honestly, I did not think this was actually possible. And although I understand they use latent humidity, I don't understand how they get the light to deflect at a certain point.

Oh, wait. Maybe I do. Perhaps they're pointing MANY laser beams, which are all not bright enough at a given moment to notice, at a certain point, thus illuminating the water-vapor there to a visible degree. From the videos, it seems as though they were blowing some sort of air stream past the display. My guess is that this thing is fairly loud when it operates.