This is uhh...interesting.
Actually, when you break it down each of those
Weng Chun dan chi movements can also occur in Yip Man WC dan chi sau when you "free it up" ... At least as I learned dan chi in the WT lineage.
For example,
if your partner strikes at a downward angle from fook-sau, we similarly receive his force with dai-bong -- much as in the clip. Then if your partner should deliver an inside gate palm strike with
outward pressure, we will also flow from the fook sau to "kau sau" (plucking hand) to direct the movement to the outside then continue circling our hand (huen sau) to the inside gate and strike.
However,
we never do such a fast, repetitive cycle with these patterned movements. Instead we respond to the force we receive. This pattern would not teach the kind of energy we seek.
BTW I have seen very fluid and varied single arm chi-sau in many other
Yip Man branches. I recall an impressive clip of Sifu Augustine Fong having a bit of fun with a senior student going one hand against two. But again,
not a repetitive patterned response like this.