The "moving hand" is a light reflection on the inside of the windshield glass, the "moving body" is the (outside) curved sideview mirror distorting the image with the changing angle of view.

EDIT: You can see it clearly in the original video (https://twitter.com/DefenceU/status/1510372750665433089) uncropped, uncut.

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Continue to see
see how you want things to be
anything but real
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#haiku