[ANSWERED] How to warp a movie to follow a mask?

[JJHP3]

I've been trying to figure what my question is so that some maybe able to give me some advice. Let's say I have a movie clip of feet walking from L to R over the length of the clip. I want to make a mask so that the clip only shows maybe 1/4 of the screen. And the mask looks like a path/river that goes up and down over the length of the clip. How do I orient the movie clip so that the feet follow the mask path? Like the feet are walking on the bottom of the mask as it wander up and down. Does that make sense? I do most of my clip creation in Motion before bringing it into Izzy, but there doesn't seem to be a way there. Perhaps in Isadora? Thanks for any advice, John

[JJHP3]

@jjhp3 Sorry to be ignorant in public - brain just not handling this well! Better example might be a curvy blood vessel with cells moving through the vessel. Getting the "cells" to follow the vessel is my problem.

[JJHP3]

@jjhp3 Well damn if a glass of Bushmills didn't clear my thinking - I can use the mesh tool and all is well!