How do i get a mirror effect for my video on imovie or imovieHD?

-i want my video so it looks like the ground is like a mirror, (im doing a c-walk video) and whenever i step id like it too look like im stepping on my foot with my foot... here is a video as an example skip about halfway thru to see the effect im talking about





http://www.youtube.com/watch?v=MGgJrHL6dbwHe says he uses Vegas 9 software, so I Imagine it is an effect within that program.