If you look at a construction ribbon, which is streched between two poles on a windy day, you will see that it vibrates up and down rather rapidly. In fact it is this same effect which makes your vocal cords vibrate, and the reed in saxophones. The difference between these and a rotor kite is that the rotor kite can continue to rotate in the same direction. This kite just seemed to roll around the sky a lot more than usual and eventually hit the ground, the same as a normal kite loops around a lot when it does not have a long enough tail. Though how this surface plays a part is still a mystery.
Lets just take it that the ear does tell the kite, somehow, which way is up.