Having watched this a few times, it seems a whole lot less dangerous (to bystanders) than the way jet skis are normally operated. These things connect to the pump-jet on the back-end of the jet ski and essentially cripple their ability to move. The only way movement can be achieved is by dragging the jet ski backwards through the water with the flyboard. This will typically be at less than a couple of knots of speed. Also, I don't see how anyone could do this activity unless they are stone-cold sober. <img src="http://www.traveltalkonline.com/forums/images/graemlins/jester.gif" alt="" /> Contrast this with the chaos and danger-potential of a jet ski running around an anchorage at 20-30 knots while people are swimming in the water.