Much too small of a footprint. Wet a basketball, or any ball, and roll it across a floor, and note how big of an area gets wet. The contact surface is so small that you would need tens of thousands, at least to do anything significant. In my opinion, and it's only that, having had these things contact mines and blow them up, can provide a sense of safety to the population that is not actually there. The people may then, thinking that a path is cleared, enter the area and come into contact with a mine that was missed.
If he is going to use a wind powered device that is disposable and cheap, in that same vein, he needs something different. If you notice , some of the toys he showed were cylindrical. A cylinder would provide a drastically larger footprint. The surface could be feathered in a unidirectional manner, which would allow the wind to push it by getting under the "feathers" , and using the same cushioned footprint as the ball shape, they would compact into a flat surface once on the ground. The only way you would be able to get enough of them in the area would be to take that concept, and make it a cylindrical inflatable device, weighted on the inside, that you could transport flat, and blow up on scene. You could transport a large number, get them operational easily using a air pump running from vehicle, and deploy them. Still though it leaves a lot to be desired.
You would need a good number of them, since you are looking at a one to one ratio , mine to device. The best thing, is just to do it in a conventional manner with mine clearing equipment.