The back squat

I watched this video from HQ this morning and am wondering about the cueing that the coach gives on their elbows during back squats (tells them to keep their elbows down). I was always under the impression that we should keep our hands as close as possible (which he does tell the female athlete), but also to keep elbows up to create a more stable base across the rear delt for the bar to rest on. Which is better?

First, it is important in the back and front squat, that we are able to move our arms independently of our upper back. What does that mean? Can you raise your arms straight above your head without your rib cage floating up? Then your shoulders have the mobility to move independently of your thoracic spine (upper back.)

Once that is determined, we can begin to consider our arms (or elbows) during the back squat. First, your elbows should not be your first consideration in proper back squat form. Set the bar comfortably on your traps, set your hands comfortably outside of your shoulders, make sure your elbows are slightly behind the bar, and your good to go. We will not worry much about your arms and elbows until, A) they are becoming really tight and we need to know why or B) the bar is deviating from a straight bar path and it is a possibility that forward pressing arms are the cause of this shift (it is more likely that hips shooting up prematurely, changing your back angle suddenly is the major factor.)

If you had the time to watch the full video, you noticed by the 7th-10th sets the athletes form was beginning to crumble. Their coach decided to keep the weights manageable at that point, only letting small breaks from perfect form. Were I coaching those well seasoned and clearly capable athletes, I probably would have pushed the weight a little further, letting the form suffer a little more (safely of course.) In CrossFit, we call the balance between intensity and technique threshold training- the constant battle between these two elements is essential in getting stronger

Additional: more important than knowing how a movement should look is knowing why it should look that way. Figure that out and you've learned, instead of just imitated.