Each little disk is a four-frame movie, all with the same face, in a sequence positive-positive-negate-negative.  Gaze at the central fixation point for ~30w, then click on the same fixation pout.  The motion will stop and you will see a strong motion aftereffect in each disk.  So the four-stroke cycle is stimulating low-level cortical motion detectors.

Obama seems to move to the left and Trump seems to move to the right.  Neither changes his average position.

Vertical four-stroke drift:  Currencies

Rotating landmarks

Each movie is four frames long, in the sequence positive-positive-negative-negatives.