Originally Posted by
Michael Wolf
Get some lifting shoes. Wear them. Take a slightly narrower stance, and shove your knees out when you initiate your squat.
You're also not going below parallel. It doesn't look like you're wholesale losing extension,but it also doesn't look like you're really getting your back tight. However, this could be because there's not enough load for you to get tight against, as well as the three things mentioned above.
If your back is healed enough that it's safe for you to begin squatting, it'll be safe at more than 67 lbs. I'd like to see a set with a bit more weight, and you implementing the stuff I mentioned above.