'Magic Moving Images'

Magic Moving Images - http://www.youtube.com/watch?v=S5W5JJXtqhw

I love the idea it reminds me of when I was younger when I had an optical illusion book and I was fasinated with the idea of such things. I tried to create one of these but I couldnt get the dimensions of the plastic sheet with the straight lines so it didn't work properly.
But I like the idea of using something in my animation which turns out to be more than it appears.