I am trying to have an elliptical mask path follow a point that was motion tracked. how can i attach the center point of that mask (not the layer) to follow the tracked point? I've tried Nulls but the path alone doesn't follow..instead the whole layer follows instead. i need this to follow a highlighted subject around.
You can't do it with a live expression--you have to use a script. I think there's one called TrackerViz. There may be others.