redivote - good start. I used to hate the squat and tried to avoid them whenever i could. I got some help on my form, and now I love them. If done properly, they are a great addition to a workout.
My suggestions:
1) Lose the weight. Practice with just the bar, or nothing at all until your form is perfect. Only then do you start adding weight.
2) I think your toes are pointed a little too far out. Your knees will follow the direction your toes point. Your heels are the correct distance apart. Angle toes outward only slightly.
3) Keep a good arch in your back. It may help to pick a point on the wall about two feet over your head and keep focused on that during the squat.
4) Think of the squat as a sort of two-part move. The first part is just your ass moving first. This happens before your knees begin to bend. Once your ass is slightly out, then begin to bend the knees while continuing with the ass. Blend this together into a smoothe motion. Pretend that you are going to sit down on a bench. That's how i learned it.
5) Focus on keeping the weight off of your toes. I push through my heels. There is actually a little gap under my toes - all weight is on the heels.
6) I see no reason for the ass to go below the knees. This can only cause trouble in the knees if you are using heavy weight and your form isn't perfect.
These are only my suggestions. Others may rip my thoughts apart as wrong, etc. but this is what worked for me. Say no to chickenlegs.
Good luck, and keep that back arched. Post another vid once your form is improved.