The way Zeny is describing this makes it sound like "Qi magic" or the "Ki master" in the above clip. And I think he is using multiple definitions of the term "kung fu" which is not helping. Kung Fu, by the way means "Hard Work" however it is also accepted as "Chinese martial arts" these days as well.
His use of 'limp' and 'loose guitar string' are just wrong.
As for the Taijiquan saying “use four ounces to deflect one thousand pounds” that is said and it is true, kinda… It is simply physics, everything and everybody has a tipping point and in a person, depending on where you hold your center it can be rather easy to knock someone over if you can find their center. Example, many good Internal Martial arts people tend to think of their center as their Dantian (a point about 3 fingers below your navel) this gives you a low center of gravity and makes you harder to push over or uproot. Now many body builders tend to have their center much higher and there for are a bit easier to push over. And if they respond with strength they, or anyone, is easier to uproot and knock down if you understand the whole “use four ounces to deflect one thousand pounds” things. However do not take that too literally. But all of this takes a connection and if someone is pummeling you with kicks and punches it is not as easy as Zeny seems to want to lead you to believe.
Now it is not magical, it is not mystical powers of Qi it is physics. Do it right and it looks effortless, but it takes a lot of training, patients and frustration to get there.
As for this bit about whole
If i show you a move, and explain the move to you, and immediately you can do the same move, then that move is only a trick and not kung fu.
Well, that is mostly wrong.
There are a plethora of moves and postures and applications in Wushu (the proper term for Chinese marital arts) that you can show someone that can be done immediately, but then that depends on how well the student pays attention, how talented they are at what they are trying to learn, and what experience they bring with them. However talking strictly in the realm of Qi (energy) projection, well then that is a trick. And if you are limp as a wet noodle and go up to someone, touch them and they fall over, then that too is a trick and you can at best claim you have taught your student to fall down on cue.
However, when talking Taijiquan, it can take a very long time to get to a point where you are relaxed enough, patient enough, and enough faith in your ability, to get to the “use four ounces to deflect one thousand pounds” but that does not mean that there is not a student out there that will not get it immediately, if shown properly. But it is very rare to find anyone who picks it up after being shown once