I agree with you Dave. Sergio is showing good use of structure/mechanics. Nothing earth-shattering here or particularly "internal" here. But then, I've always figure all the "internal" stuff was just good biomechanics anyway without resorting to "chi flow."
He is unnecessarily dramatic at times. But I guess showmanship helps make the point. And it is a little "snake oil-like" when you have a student pushing you on the shoulders and you aren't moved because you can roll it off, but then you push right into the student's center so that he IS moved! Or you have a student pressing on your hip with the palm of his hands and he can't collapse you, then you stab into his hip with your fingertip (more painful, more focused force) to show how much weaker he is than you. So while I think the basic message is good, the delivery was a bit over the top. But that's just my opinion!
There is good stuff here though. Sergio shows good structural control. A lot of that is because he never has his weight back on his heels and he is sinking his center forward. But isn't that what all good WCK is supposed to do?