Originally Posted by BendtheBar
Good point. Piggybacking this with what Rippetoe said, knees forward would also comprise hamstring tightness - if I am understanding what he said correctly.
Ye this is something that helped me, keeping the tension on the hams keeps my knees back and feel a lot better squatting. Also looking down and forcing my shoulders into the bar as opposed to head back and around the bar has made a huge difference with locking my back in a decent position before squatting and avoiding the forward lean in the hole.
In regards to the first video, I think his problems come from his foot position. Looks to me like he's trying to go wide stance without turning the toes out like Dave Tate teaches. I find it near impossible to force the knees out like that and the hips lock up, that can pull at the torso and also forces the knees forward to make depth.
I could easily be wrong.