The "water whip" movement is based on the Tai Chi posture "single whip."
The waterbending forms shown on the scroll is the 24-step form of tai chi, sometimes called the Beijing form. The writing on the left side of the scroll says "waterbending practicing first set."
This is the second appearance of The Cabbage Man. He references the first with the line about how this place is much better than Omashu, where he previously appeared.