How are this helicopter's blades perfectly timed with the camera shutter?
If the rotor is spinning at 360 RPM, typical of helicopters, that's 6 revolutions per second, and 5 blades go by each revolution.  6 x 5 is 30, so you have 30 blades passing point X in any 1 second period of time.  Unlike film at 25fps, video is shot at 30 fps, in perfect sync with the blade passage, so the blades look stopped.  If the rotor was going a little faster or slower, the blades would start to move.

The video camera is in effect working like a stop action strobe camera.