I have two videos he made. 1 is just a simple wind up and down (Chopper only) and the other is a wind up, but he used his hands as solenoids (hope i spelled that right) to create a Hi-Lo sound.
Videos:
Hi-Lo: http://media.putfile.com/Hurricane-Chopper-Hi-Lo
Steady: http://media.putfile.com/Hurricane-Chopper-Alert