Flyscreens and gravity and magnetism

Have you ever looked through two flyscreens at once?  It has always facinated me how with two very simple objects with simple patterns give off really crazy patterns.

Two flyscreen like objects: one rotating about its X axis the other is still.

In the animation above I think that we even see different parabolic lines that are reminicent of magentic fields

Magnetic field lines from two magnets