Steel Tiger
Senior Master
A few glaring examples: About 3:20, he turns what I'd call a hanging or wing 'block' into a driving arm bar by stepping (taking his whole body) through the opponent's space. At 4:45, I learned that shoulder bump in another CMA. Since your momentum is meeting his, it's very effective (and we found it can be intensified by grabbing the arms he throws out to keep his balance and pulling him around you--and down). At 5:15, similar to what I learned as the 'double down' block--lots of power because of body movement/weight.
One thing to remember (which you have pointed out already with "he's a body fighter) about most CMA, particularly those styles lumped into the "Internal" category, the body is a fist. Basically if you miss with a palm strike it becomes an elbow miss with the elbow it becomes a shoulder strike kind of thing. And Xingyiquan is very much into hitting with as much of your body as possible. In the palm strike in Piquan the idea is to focus all your available body weight and power into that palm strike. The force comes downward and forward and I am told at higher levels it has an upward force as the last part of the strike as well.
Xingyiquan looks rather simplistic and boring to many and there really does not appear to be much to it when you look at plain forms. But it takes a lot of time to gain the alignment necessary to produce the power that Xingyi is famous for. Simply put, Xingyi hits like a truck and it isn't magic it is training.
And I want to add your posts here are helping me make a rather hard CMA training decision, thanks
With the concept of the body being as a fist there is more than just moving into an opponent's space. What you really needs to consider is moving completely through that space, almost as though he was not there. As far as internal CMAs xingyi is the most obvious at expressing this as it tends to move directly into and through an opponent. The longstep, half step combination foot work of xingyi really emphasises this concept and lends momentum and power to it. Bagua tends to move through an opponent in an oblique fashion, and taiji seems to draw an opponent out of his space.