I didn't understand what the OP meant when I first read this but I just watched the video to try to figure it out.
I use a Klippermate dropweight that is obviously constant pull and has only flying clamps. I not only release the "trailing clamp" but I only use one clamp period when doing the crosses. I tension the cross by dropping the dropweight bar and then release the flying clamp from the previous cross and then use it to clamp the current cross. Is this not typical?
I figured it helped to take up a bit of the drawback from clamping and by appearances is seems to. I've strung less than a dozen racquets in my life though so am curious.