See the problem is this...Your confusing Chi Sau with gor sau or actually sparring. Chum Kiu is simply a form which gives you techniques to practice in the air that can be broken down into drills against compliant partner until your muscle memory becomes natural and your ready to intergrate it into freestyle sparring where anything goes not just WC...
Chi Sau is a compliant drill that your partner does with you to teach you how to use certain elements of WC when you have a bridge,sticking to your opponent are attempting to take the centerline or control his structure. it teaches you how to control his structure, centerline, and bridge. Thats what chi sau builds. it allows you to learn to relax when your toe to toe and get use to sliding through some ones defenses and manipulating their structure to your advantage...Chi Sau is simply a drill...A Bridge to real sparring...
Only in sparring can you truly realize the truth...
But before we get their your Video you post are not real sparring...they are compliant drills where two people are vibing for the center and trying occupy the same space ie both are bridging or trying to bridge. Only the dominant one controls the bridge nullfying the others bridge. You want to prevent your opponent from sticking to you. But at the same time you woant to stick to him so you can control his centre.
Your clip is your teacher actually taking his opponents centre and controlling his structure. All the while he does so while maintaining a constant bridge by Faan Sau.
Wing Chun Not bridging or Sticking Clip
Wing Chun Bridging and Sticking Clip
Can you understand the difference?
When I punch an you throw your arms up I am going to gain contact with your arms ie bridge. if you strike an i intercept or cut off your punch with a bil sau i have a bridge. But as I bridge im striking you back at the same time right? Everytime you get in striking range I bridge. Everytime I get in striking range I bridge. Sticking is simply staying close to your opponent the way a Bee does or the way an aggressive street fighter does.
I strike while bridging...if there is no bridge to obstruct my strike i strike anyway...if you attack i bridge and strike. If you drop your hands i leak in an strike. The main thing is I want to keep any potential attacks nullify so as I gain entry i pak da or lop da to stop or immobilize your lead hand from striking me and also to disrupt you for a nano second. Allowing me to be ready for your power hand!