As PetaPixel put it when describing an older clip,
Since each frame has to ensure the blade is in the same position as the last it therefore needs to be in sync with the rpm of the rotar blades. Shutter speed then needs to be fast enough to freeze the blade without too much motion blur within each frame.
Here the rotor has five blades, now lets say the rpm of the rotor is 300. That means, per rotation, a blade is in a specific spot on five counts. That gives us an effective rpm of 1500. 1500rpm / 60secs = 25.
Therefore shooting at 25fps will ensure the rotor blades are shot in the same position every frame. Each frame then has to be shot at a fast enough shutter speed to freeze the blade for minimal motion blur.
Tangentially related: Lance Armstrong cycling without pedaling: