How do I create the glitch effect like

I’m trying to recreate the glitch effect between every page like in

If you go into the site, then click start, then click contact. you will see that between the home page and the contact page there is a “glitch effect”.

I don’t get it how do I do it?

there’s nothing really “3D” about this, might be best to check over at Browse (1) - Shadertoy BETA
for a more applicable solution perhaps?