Correct. The frame rate of the video vs the rotation rate of the blades happens to coincidentally line up making for almost stop-motion photography.
Here’s one of my favorites for that:
It’s a vid of a Czech Air Force Mi-24 Hind attack helo doing an airshow demonstration. Throughout the demo you’ll see the blades barely turning. No helicopter could fly, much less maneuver aggressively, with the blades barely moving.
The actual Hind has 5 equally spaced blades on the main rotor. At many points in the video you’ll see that it appears to have 5 equally spaced pairs of blades close together. That’s also an illusion, when the next blade almost gets to the same spot in the rotation when the next frame is taken. Ina few spots you can watch the blade pairs merge or split; sometimes 5 blades, sometimes 10.
More fun w frame rate:
The rotor on a Hind rotates clockwise when viewed from above. Which means the blades are going forward on the aircraft’s left side and rearwards on the right side.
In most, but not all, of this video you’ll see the blades going forward on the right side. In other words, the rotor appears to be turning backwards.