>>7226688A little bit of a tuck is natural, however you are almost squatting to the point where you lose the arch in your lower back completely. You also need to look up slightly and dig your head back into the bar. With your head positioning the way it is, you are very likely to end up doing a squatmorning out of the hole. I personally have switched from low bar squatting to more of a high bar squat. For me it is easier to achieve depth and keep my torso upright with a high bar squat. Don't low bar squat just because every one tells you too, find out which is more comfortable for you and gives you better form. Make sure you aren't letting go of your arch at the lockout.
My recommendations:
1. Work on hip and hamstring flexibility.
2. Practice arching your back at depths. (This goes along with flexibility)
3. Look slightly up and keep your head back.
4. Experiment with bar position.
Your depth looked good and your were sitting back as well as one would hope for in a free squat. I don't have a front view so I can't really tell how your knees looked.