Pelvic rotation?

I can safely say that I don't I have had my gait checked a few times and all they tell me is that I land midfoot.
But I was just curious if the ponytail/necklace test is a sign of hip rotation.
The other day there was a girl running in front of me and her ponytail was going crazy side to side so I started to wonder if my ponytail had the same motion so I reached back and put my hand so very lightly on back of my ponytail and to my surprise it didn't move at all or hardly.

Edit
Maybe it's the upper body rotation that creates the ponytail effect...I don't know, all I know is that I know a little of everything and a lot of nothing. Sorry for my rumbling.
 
Now that you ask, yes, I am aware that when I "change gears" and start to run fast and freely, my hips open up their motion as well.

This is especially noticeable when opening up on a downhill, and letting the legs "spin" as gravity contributes velocity and I'm simultaneously focusing keenly on my running form.