Originally Posted by
BareSteel
It may be as easy as cueing that right elbow UP. Now that you are aware of the problem, you may begin to feel that elbow start to point down. Force it back to the correct position. I notice that the problem worsens slightly as you attain depth. That's a clue to me that it's poor positioning on your part, since structural asymmetries are usually apparent throughout the duration of the rep. Plus, you look symmetrical at 0:11, but as the set starts this deteriorates.
If I suspected an arm length asymmetry, I'd look to see if the center of the bar is plumb with the center of your spine when you squat, If the bar is off center, but you grip is symmetrical, you'll have to move one hand out wider (or narrower) until the bar is centered.