around 1m40s the object rotates simultaneously with camera rotation, twice, and at twice the angle of rotation the camera makes! now think of how if you rotate a mirror some angle alpha, then the reflected view rotates an angle of 2 alpha. So to me this is a tell tale sign of some optical effect. Do I have a complete explanation? No, but then again there is no complete specification of the observation: what is the sensor layout and optical setup like?