You look really unstable, bro. I'd second sitting back just a little bit. I train at Rippetoe's gym in Tx (I'm currently deployed however). When I started there, my squat was pretty unstable (i.e. jerky and not smooth descent). I focus now on keeping the bar over the center line of my feet, maintaining a fluid descent, and utilizing the stretch reflex at the bottom by getting my ass back and tension on my hamstrings throughout my warmup. Every set, every rep is focused on feeling proper form. The bar looks like it travels forward toward your toes on the bottom half of your descent. If you were looking at yourself from the side, you would probably notice a bit of a "figure 8" in the bar's path of travel. Keep your upper & lower back/abs locked tight and, as I train at Rip's, I'd recommend a neutral head position. Your writs look to be in a really weak position. Try to get your elbows up a tad and get your wrists into a strong position. It will help with your lat/upper back tightness. Lastly, possibly turn your toes out just a little more. Looks like your knees aren't totally tracking to the toes directly. Just my 2 cents, though.
How much hip mobility work do you do? I'd also recommend some shoes. I used to squat barefoot, then used chucks, and now have some Oly shoes. I'm not sure but I think the lack of arch support/stable base lead to my knee problems in the past year. I tore my PCL completely in my right knee last summer while squatting bare foot for a year or so prior to that injury.
These are just little things, however. Not bad at all. Just keep working hard, man.