Dave McElderry wrote:Pretty cool. Right at the beginning the blades have a slight turning motion, and in the last few seconds there's definite motion, so this may be legit.
It is legit. Most helicopters are designed to operate within a narrow rotational speed range. In normal flight, it usually stays within plus or minus 1% which is vary nearly constant. The rotational rate is related to the size of the rotor. They want the tip of the rotor blade to remain subsonic, so, the longer the blade the slower the rotation. Since most video cameras have fixed frame rates, I would assume that this helicopter has a rotational rate which is an integral multiple of the frame rate. Say 300 rpm and 30 fps. It also looks like the shutter angle (shutter speed) was adjusted to eliminate motion blur of the blades.