Too bad about the off-center framing. Nevertheless I think I got the general idea, and to be frank, I don't care for it. While this kind of high sideward flicking pack can work in sparring, depending on other factors, I do not believe it is good training in a drill like chi sau. Here's why: Chi-sau is just a drill designed to train specific attributes. One of these is bi-lateral foward intent and forward springy pressure (yau lik). Another is learning to sense and control your opponent's center. And above all when both arms are engaged, you don't let go of one arm and use both arms to control one of your opponent's. Yat fook yee, mo yee fook yat. One arm controls two, not two on one!
When you do the high pak from fook, you free your other (tan-bong) hand to spring forward and strike. So far, so good. But you have just released your opponent's other arm and for an instant are using both your arms to release his fook and free your tan-bong hand for the punch. If he has good forward spring he will hit you first, or at least trade punches with you. Of course, you have the high-line and may trade your shot to the head for his body shot. You are also bigger, have longer arms, and are more experienced. So I would assume that you usually get the best of the exchange. That's OK in sparring, as I said before. But is that good chi-sau?
I admit, also am quite fond of using indoor pak-da in chi sau. But I use a firm pak below the bridge and step in with my pak so that my forearm forms a low lan sau and traps my opponent's other arm and controls his center of gravity. For those who know the WT system this is the opening of their "Second Chi-sau Section". Applied against the right pressure at the right moment, it is beautifully efficient and effective. Or as Yak noted, applied at the wrong time and wrong situation it can get you clobbered!