After watching the DVD and reading the book you can do, like Sam Sachdev, a Home Test for Parallel Universes and impress your friends. (Please keep in mind they need to know basic Physics). The experience is reported online here.

It's a derivation of "the double-slit experiment" , the touchstone of quantum weirdness, and it was first made by Thomas Young, 200 years ago. I remember doing it in high school and don't paying too much attention to it. At the time it didn't had the significance it gained over the last couple of years.