A pen writes a thick cursive scribble, the scribble floods the frame, and its ink becomes the background the next scribble is written on — a two-colour loop where the drawing is the room the next drawing happens in.
Reference is the measured rebuild of the source clip — width traced straight off the pen's speed, the flood as a zoom with the stroke swelling on its own curve. The other three are the same engine fed a procedurally generated scribble and an authored palette.