Matt, possibly fatigue but I doubt it, KK isn't one to let his form break in training. He's probably just trying to mimic his DL. Pavel has written that Bolton's deadlift is more like a swing while KK's is all leg drive and then pull. So a swing focusing on hinging back might not be the most productive for Konstantinovs. If you watch closely, it seems that his shoulders come up first, pulling with his back, and then his hips snap through at the top of the swing... just like his deadlift.
And for those who haven't seen his other videos, he has pulled 939 raw and beltless, benched 584, squatted 738 (not all in the same meet); and done ridiculous numbers on other lifts as well. Deadlifts with full back flexion off a platform with 600+, machine pushdowns with 400, 55 consecutive pullups, ab wheel and hyperextensions with 60kg, etc.