You'll get this kind of effect when you hold a magnet up to an old CRT display. It produces this beautiful rainbow seizure like art. German artist Carsten Nicolai set up an installation that uses the same magnetic deformations to make more of it.

"crt mgn" is primary composed of two pendulum arms capped with magnets. Each of it will swing over an old CRT display where it will morph and tweak the lines displayed on it to illustrate the transformative force of the invisible magnetic fields. Check it out in the video below:

[Laughing Squid]