We can only see what we can see.
Seeing is very subjective which is one reason motionanalysis is good data.
You probably don't see xfactor either.
When I look at the Barry clip, there is for example a prominent "sit" between frames 7 and eight. This appears to me to be primarily due to flex in back leg, NOT bend at waist, and NOT rotation of back leg.
But we can only see what we can/want to I suppose.