Agree with Mercury on lighting…HOWEVER, I see one very big glaring problem. You are initiating the squat with your knees. This. Is. BAD. It is the opposite of what you want to do with an Ed Coan style squat or a Louie Simmons wide squat. This is one big reason, maybe the only reason, you are having trouble going to parallel–stop it immediately. Initiating from the knees makes it very easy, almost inevitable for many people to squat ONTO their knees, instead of BETWEEN them. It is hard due to the video angle and low lighting to tell if this a problem for you, but it very likely is. Go check out this for learning how to squat between your knees properly–
The Video FitCast- Episode 6 - YouTube --the first portion of this is absolute gold. Listen to everything Dan John.
You initiate all squats with your hips, not your knees bending. Now, there is a borderline exception for Olympic squats, but not enough to matter for you–besides many olympic lifters initiate their narrow stance squats at the hip as well so it doesn’t really make it ok for you (their timing and pace is so fast it is sometimes hard to tell on video, but in person it’s easier to see).
So, no matter what kind of squat you are doing–parallel, wide, olympic, front-- always, ALWAYS initiate from the hips. Break the hips BACK, not down, first. This doesn’t mean you start to do a good morning or a romanian deadlift. But it does mean the hips are the first to move.
Plus side, your back looks neutral and stable in the hole, so you’re not inducing lumbar flexion. I would look at the adductor/abductor and hip flexors mobility and soft tissue quality for getting deeper, as well as your ankle mobility (yes mobility is much different than flexibility, something I may have mistermed in my last post unintentionally as I was stream-of-consciousness posting, I don’t remember).
However, it all starts with initiating at the hips FIRST, and simultaneously pushing the knees OUT, not forward.