[btilly]

Here is a simplified picture.

The propellers are being pushed into a spin by the difference between the airspeed and the groundspeed. (Note that the propellers are locked to the ground by the wheels.) As they spin, the blades generate lift. That lift then pushes the craft forward.

Take away the difference between airspeed and groundspeed, and nothing is keeping the blades spinning. Therefore the system will run to a stop due to friction.

The connection between spin and lift is mediated by aerodynamics, not a mechanical linkage. And aerodynamics allows the vehicle to be pushed faster than the spin. Which is why, if you get friction low enough, it can go faster than the wind. And not slightly faster, but a lot.