Moonwalk

The legs walk forward and the body travels backward, so the eye receives two contradictory reports at once. The effect is a glide with no visible push behind it.

It reads as weightlessness. Nothing in the movement explains where the travel comes from, which is why the step turns up whenever a character is meant to look like they are not quite bound to the floor.

The performer slides one foot back while the other lifts at the heel, then swaps, so the weight never lands on the travelling foot. The dance is older than its famous name and was long known as the backslide.

The floor and the shoes decide whether it works. A smooth surface and a hard sole let the foot travel without catching, and a soft sole on carpet kills it entirely.

Shoot it from the side, at or below hip height, with the feet inside the frame. From the front the leg movement is hidden and the glide loses the thing it contradicts.

Use it for performance, for comedy, and for a character who should look like they are moving without effort.

Skip it when the shot needs weight. A moonwalk cancels the sense of a body pressing into the ground, which is the opposite of what a dramatic entrance usually wants.

A double dolly moves the subject and the camera together so a walking figure appears to float toward the lens. The legs there are doing ordinary work and the camera makes the strangeness. A moonwalk puts the contradiction in the body.

Reversed footage also makes people travel backward, and it gives itself away in the hair and the clothes. A real moonwalk travels backward with everything else behaving normally.

The result is an ordinary walk, because the contradiction is the hard part and the model smooths it out. Ask for the body to glide backward while the legs walk forward, and say there is no visible push.

The other failure is obviously reversed footage. Hair and cloth move the wrong way, so state that the motion is genuine and the rest of the scene runs forward.