Talking of Yi Quan, did you know that we have at least one poster here who says that he has practiced 5 years (if my memory serves me correctly) of EXTERNAL Yi Quan? LOL!
Going back to the video, I believe that a lot of the body mechanics of an internalist cannot be seen by simply observing a video as even those happen at an internal level.
However, on another level one can still see the relaxedness (up to a point) and the flow during the motions, as well as the posture allignments.