DodgingRain

I am not a student of Mr. Calandra's, nor his teacher.

I believe it is a combination of the camera angle being slightly off center, as well as the human body not being capable of replicating a perfect hinge.

The goal of Mr. Calandra's teacher's style is to rotate, just like a door hinge. Unfortunately the human body was not designed to move in that way; which is why it is so difficult for others to deal with, as well as why there is so much training time necessary.

Because the human body cannot fully and perfectly replicate the action of the hinge, we can only get closer and closer to this ideal.. the person who can get the closest to establishing a real hinge in their body will have the most skill.

So you have to establish a vertical axis in your body to act as a hinge for your body to rotate on. A hinge has a fixed point, a point that does not move (cannot move), as well as the part that rotates around this non moving fixed point.

In the video, he is demonstrating how he can produce a vertical axis within his body to rotate on like a hinge. Establishing this axis in the center of his body (spine) makes him very agile and able to neutralize and redirect without displacing any space (moving in space). You can also establish this axis on either kua/hip and switch to either side without moving in space, which produces different effects.

In his system, allowing your axis (hinge) to move in space (rather than stay fixed) is considered an error. Imagine if the door hinge was not screwed in tightly and wobbled. Imagine what happens when a wheel axis is bent/loose. The reason the rotation has any power and works the way it does, is because there is a central point that stays fixed/does not move ("wuji"). If you allow the axis to move and displace space, you are wobbling, and your potential power is dissipated.

The point of his knees not moving laterally was to show the difference between his style and other taiji styles. Most every other taiji style (chen village style as well) moves their axises alll over the place - the biggest most obvious indicator of this is the knees moving side to side. If the knees move laterally like that, it is guaranteed that the spine (or any axis) is moving (displacing space/tossing) as well.

Of course you can combine this with rounding out and making the straight parts curved and direct it to the ground, but this was only a demonstration of a specific principle that has much more implications and applications later.