Definately like they said RELAX and loosen up. And when your shadow boxing visualize you opponent in front you. In the vid if you had someone in front of you you would have been hitting there arms. Couldnt really see your feet but it looked like you were turning into your punches all right. Also it almost looked like uppercuts on some of the punches you threw. You need to change levels by slideing your back foot out a bit and bending your knees so you can get down there and throw a good shot. Never bend at your waist, and if you have to only slightly. Keep your hands up to your checks and eldows nice and tight against your body. Maybe work on your posture. Other than that you look like you got some speed and good power so keep it up!! Also one last thing when you throw your hook try to make your forearm parallel with the ground. Keep it up like I say you look like you good some natural ability.