But they aren't the best in WC and that's the entire point of the MMA vs Kung Fu mess. He wasn't trying to fight against legitimate Wing Chun fighters and even stated himself that his focus was on exposing the fakes. So even after you see that the WC fighter isn't that good, you are still trying to learn and see sticky hands from that person. Why?As I said, those in the videos are supposedly the best in Wing Chun already
Find someone who knows how to actually use the technique and learn from them.
Just because someone says they are "the best" doesn't mean that they are. If you can't understand this, then the first thing I would focus on is learning how to find those who actually know how to use the techniques. Once you find someone who knows how to use it then learn from that. Don't trying to learn and see stuff from people who claim they are the best.
I know tons of people who don't claim to be the best but know how to use the principle of sticky hands. Concept is really easy. When you are within close range "grappling range" make sure your arms and hands stay connected to your opponents arms to interfere with their punching and grappling techniques. You do this with the goal of opening opportunities for yourself, while denying your opponent the same opportunities. This is done in close range. If you are throwing punches long range then you won't be able to use it, because it's not the range in which it is used.
Hopefully this will help you understand it. However, if all you want to do is try to learn from that video that you posted, then I can't help you there as you will not learn anything from that, be it Wing Chun or MMA.