Even though Moshe is an idiot, if there is a "link to the ancestors" as he so vaguely put it, then it's probably this IMO regardless of his arrogance.
Wing Chun ultimately has everything to do with control of your own body. All the drills, forms, and chi sao should, if a competent Sifu is present, teach you how to control yourself. You can only control another efficiently if you first are able to control yourself. For example, real fighting is the combination of soft stick, hard stick, distance, and structure when the opponent doesn't just let you hit him. You attack, the opponent intercepts but the distance hasn't been moved. That is soft stick where as soon as the skin stretches in your own arm and the opponent hasn't stopped his forward power to neutralize, you can switch to continue the attack. Hard stick involves moving the structure into the opponent whether he's intercepting your attack moving towards you or you're moving into him to intercept his attack. Hard stick involves your body active while your arms are passive(like pushing a car) letting you switch using the opposite principle as soft stick. As soon as his power stops moving forward you can switch immediately just like a spring releasing. Fighting with wing chun is the constant back and forth between these principles. There's of course much more but all of this, all of Wing Chun, can only be applied if you can control your own body and it's reaction to force. Has nothing to do with your training partner or opponent. If there's anything that could possibly be the "link", I would put my money on that guideline.