Very interesting idea .
After looking into this abit more it seems that he is already selling smaller electric versions (Stingray 500)
And if anyone is interested in how this works, I looked at the assembly manual and it seems the motor drives a central boom which has two belts connected at each end wich go to each of the motors.Some pics from the manual to show what I mean. Definitelymore complicated to build than a regular quadcopter, and also harder to fly.
So the blades all spin at the same speed and to change the angle the pitch on them is adjusted via the 4 servos, similar to how 3D RC helicopters work.