In the video one magnet (green) and two pieces of iron (purple) provide the energy for turning the static force motor.  Instead of a magnet and two pieces of iron, a spring with tension could be connected from one arm to a center rotating pin.  An air spring (more easily controlled) could be connected from one arm to a center rotating pin, and pull in for forward (air pressure in left chamber), push out for reverse (air pressure in right chamber), and be in the middle for neutral (air pressure the same in both chambers).