Yes, there were videos taken at the world record Mentos/Diet Coke demonstration in Leuven, Belgium. There are several on YouTube already, but none that give you a great overall view (yet).
can someone please explain why Mentos have that reaction with Diet Coke.
they explained it on mythbusters. it has to do with the texture of the candy, the aspartame and the caffiene if I remember. just run a youtube search for mythbusters diet coke mentos
Yeah, the surface of the candy acts as a catalyst, it has millions of tiny pits in which gas bubbles can form. Aspartame has a bad effect on the stability of the carbon dioxide-water solution, making diet Coke more liable to release all its gas at once than regular Coke.
http://www.youtube.com/watch?v=K3wQsLTYL1I