The camera angle isn't the best but my general thoughts are as follows:
1. You need to be building tension on the way down for a proper stretch reflex/rebound at the bottom. Control the bar don't just fall into the bottom of your squat.
2. By the relaxation at the bottom I can just tell your knees aren't being driven out far enough. Push those knees out to the walls. Once you think they are out enough..push them out more.
Try these two things and get a better camera angle so we can see what your legs are doing at the bottom.