WowSee how the extension isn't straight down. It's at an incline which originates with inclined pelvis. The skis go straight down the falls and he tips his toes down to land. As the tips touch down he immediately absorbs and allows the knees to go under laterally. This is in fact the end of the turn. The top of the turn is the extension. Notice that all the rotational legwork is done during the flex. He keeps flexed, goes over the top, stays flexed in the foot-pull-back and only then does he extend. He extends vertically in relation to the slope. So in the bottom of the trough (Not Before), he is standing vertical, then standing almost back up the hill on the facing slope of the next bump as he sucks it up.

See how the tips touch down first.
See how the fully extended legs and body are aligned linearly and how the whole body is inclined at full stretch.
See how on flexing the knees, rotation at the knee can occur and also at the ankle. The upper-body is countering to keep itself pointing down the line. This is one of the places less-skilled bumpers spin out, miss a turn and go for the traverse of shame!

Are the hips tilting?
Yes. That's where a small amount of angulation is occurring. The thighs are both rotating. This allows the knees to go lateral. In the Piste practice shots, there's whole-body rotation as well.