Just a few things:
1. I would suggest picking up 16+ ounce boxing gloves when doing bad work, it will literally save your hands. Not to mention it will increase your hand speed and you can hit harder safer so you get better work outs.
2. You drop your hands constantly, especially after the jab. Snap the jab then straight back to your face, not to your chest then to your face.
3. Your kicks look sluggish and weak, also throw them at the end of your combination's as you circle away.
4. Would be good to practice some movement while using the heavy bag. Practice your distance, bobbing/weaving and footwork as you move around the bag (also you should be moving around the bag in a various directions to simulate an opponent)
But keep it up