You're pushing the hips back slightly before squatting down and leaving them back throughout the movement. So when you drive to stand back up your hips are too far behind the bar and extending those knee joints is causing you to to shoot your hips up. If you look at the videos you can see that you bring your hips in to finish. Make sure you initiate the movement by squatting with your hips straight down and keeping them underneath you the whole way.
Your hips seem to be a little tight. Specifically your external rotators. Make sure you're really loosening up the hips before you squat. I suggest doing hip circles, leg swings, external rotation stretches, and hip flexor stretches. I wouldn't say that movement of the feet is from tight quads. Having your feet pointed out isn't a big issue. Just find a position that's comfortable for you to squat down without moving your toes out. Besides, you look like you have long legs so it's naturally going to be a little more difficult to squat with perfect form.