Part 18:
This video deals with the inverse version of the dual super obi/ani spins. Instead of a falling movement in the front of the body, it is generally easier to make the first spin large and tighten into the second and the then the backwards stab of the inverse obi/ani. The general effect is more of a spiral than a vine down.
Part 19:
This video deals with the full inverse dual plum flower. In a lot of ways, it is easier than the standard version. I present two slightly different versions of the spin.