I don't really see her drop her elbow. Instead, I see her elbow start low and then raise. But it is only low relative to flat ground - not to her shoulders which are tilted so the back shoulder is lower than the front shoulder prior to shoulder rotation. Position relative to shoulders is what really matters. Now you could argue that the shoulder tilt is an issue and I might agree depending on how she gets into that position. For example, does she tilt in such a way that her head moves towards 2B?
She does bend her throwing elbow to less than 90 degrees but that is not uncommon and not cause for concern to me.
What really stands out to me at the 11 second mark is that her glove arm is extended straight while her throwing arm is bent. In other words, no "equal & opposite". I've watched Tom House take a kid with a poor "equal & opposite" who looked out of sync and fixed his "equal & opposite" and gave him good timing. The kid ended up looking smooth and back in sync.
I suggest working on this pitcher's "equal & opposite" and then see what the throwing arm looks like.
EDIT: Any time a pitcher has enough time in their delivery to make unnecessary movements, they may have too much time and should probably speed things up. I think this pitcher could probably stand to move faster and get into front foot plant sooner. And that may clean up her arm action.