Maybe we can help him and you out all in one go. Watch set 1 (I didn't watch set 2) and tell me 1. where your friend's gaze is 2. when his knees cease forward travel during his descent, 3. whether he appears to be driving upwards from the bottom with his hips or his chest and 4. whether he's allowing his back angle to become sufficiently horizontal for our model
1. He's looking a little straight ahead rather than down at a point 4-6 feet ahead of him on the floor, 2. They don't, at least in some reps, stop coming forward until he hits the bottom. They should get to their final spot by 1/2way down. 3. He's driving with the chest, which is related to the fact that 4. he appears to be trying to keep his back far too vertical for the way we advocate squatting around here. Basically, he's doing high bar squats with the bar in the low-bar position.