FYI....sorry for diversion.
The mask tracking effect is just one of the new features I've been drooling over, although I wish it was a mask shape you could add more points too.
For polygon-shaped masks, you can add and remove points to a mask as follows:
Note: You cannot add or remove points from ellipse-shaped masks.
•To add a mask point, place your cursor over a mask edge while pressing the Ctrl Key (Win) or Cmd key (Mac). The cursor changes to a pen shape with a "+" sign . Click to add the point to the mask shape.
•To remove a mask point, place your cursor over the point to remove while pressing the Ctrl Key (Win) or Cmd key (Mac). The cursor changes to a pen shape with a minus sign . Click to remove the selected point from the mask shape.