When you put a video track with video over another video track with video, it overrides it, allowing the track at the top to go over the one at the bottom.
Basically I want to make it so that where ever the top track is, the bottom track can only show.
Example:
The top trap has a masked circle.
The bottom track has a solid color.
I want to be able so that wherever I move that circle, it is where the the solid color shows.