It could be multiple mobility issues. It almost looks like you are doing a low bar back squat because on the initial movement your chest goes down and your hips go back.
When you squat, you want the hips and knees bending at the same time. That will cause your hips to move straight down.
Also it will help if you start with your elbows pointing straight down. If you look you have your elbows a little too far back. This correction will make your torso more vertical as well.
You can see in this photo
how Audra has her elbows in relation to the barbell.
You can do Pause Back Squats to help you get a better feel for the bottom position and Front Squats will help as well.