Description: This plugin takes two strips as input and splits the first into 
Description: 3 verical slices. Then, over the duration of the plugin, 
Description: the left and right slices move down, and the middle one moves
Description: up, exposing the second strip.
Author: Michael P. Shimko
Email: shimko@maui.net
Website: http://www.maui.net/~shimko/Tutorials.html