Are there things Yip Man knew but didn't teach?

[jlq]

The key in the above video, IMO, is timing. The guy on the right did a set-up jab and looked like he was about to follow up with a straight right - In the beat between these two moves (a vulnerable time) the guy on the left struck with his own decisive attack and followed it up to its conclusion, not giving the other guy a chance to recover.

Had the guy on the left struck a micro-second sooner or later, his first punch would not have effectively interrupted the other guy's own timing (and mental balance). By the third step and punch, the other guy's physical balance was broken as well and the fight was effectively over half-way across the ring.

Absolutely! In Wing Chun (and traditional Gung Fu) there are a lot of sayings and concepts pertaining to "timing" and strategies that allow one to take advantage of it- one is "Sin Faat Zhai Yan" (basically, "start first, arrive first") another one is "Hau Faat Sin Zhi" ("start late, arrive early"), among many others. You bring out two essentials to the Wing Chun (in fact, many southern Gung Fu styles): one is "interrupt" the other one is "break", in many schools you can find these among the list of "key words" of the style.