Butterfly kick and twist practice. Needless to say, I need more practice!
Including an analysis of the "dip".
Please note that movements were exaggerated for demonstration purposes.
Exhibit A demonstrates the dip at or above the horizontal plane.
A1) Lower Body Full Squat (Horse) Position
A2) Upper Body Maintains At or Above Horizontal
A3) Back Remains Straight & Engaged
Exhibit B demonstrates the dip below the horizontal plane.
B1) Upper Body Dips Below Horizontal Plane
B2) More Difficult to Hit Full Squat Position
B3) Difficult to Keep the Back Straight & Engaged
I believe dipping below the horizontal plane, although more difficult, is technically correct.
It requires a more explosive jump and strong lower back muscles.
The lower the dip below horizontal, the more control required to maintain momentum for the jump.
2008 Butterfly Kick Films