Looks like this one will need a little more attention. What I like to do is have them do a few squats without the bar(squat stretch position - hands together, elbows inside knees) and block the knee with my leg to emphasize proper knee position. A little hard to explain over the internet I suppose. It looks like the TUBOW was set up inside her knee as opposed to right in front of it. Try to get her in the right position without the bar, and then use the TUBOW on the empty bar and warm up sets. Slowing down the descent usually helps as well