Re: Yet another "starting strength" and "how's my back squat" thread.
This may be redundant as i haven't read every response. You are right, your knees are initiating your squat, which is pretty much the epicenter for everything else going on. Push your hip back. I kind of think of it as trying to keep my knees in place and rotating around them. not the most precise thing but it helps me. be that as it may, essentially, because you're initiating with knees forward rather than hips back, you're moving forward onto your toes, and you're heels are raising off the floor, which you can see around 0:44. i would also imagine that you're knees are moving inward as well, but i can't be sure. push them out, especially as you stand.
because you're forward, on you're toes, the bar path follows. it essentially dives forward as you go down, then forward again as you come up, which you can see around 1:30. the bar path turns into a triangle of sorts. interestingly enough, on the very last rep, you semi-correct the knee forward fault as you're coming out of the bottom. the weight gets heavy for you're previous technique, you can't pivot around your forward knees, so you pull them back, get the shin closer to vertical, and you stand up. it's kind of like a string is pulling your knees back, and that's an imagine i try to think of as i squat. also, on that last set it seems that you're hyper-extending you're trunk coming up out of the bottom of the squat, but that's secondary.
things to think about maybe.