Rolling shutter effect is a known phenomenon, which can cause interesting video effects such as helicopter propellers “freeze”, bend etc.
This video was shared as an example of the effect:
The video is a CGI artwork by Joshua Drury. It was not even meant to be an example of rolling shutter effect.
Here’s one real example of the effect when the camera shutter speed and frame rate matches the helicopter’s rotor – by Chris Fay.
[…] UPDATE: The windmills are fake. […]