The arms and legs are very smooth and nice but that just makes the stiffness of the body more obvious. Try to get the spine to spring a little bit and the head to bob a bit in relation to the body and not just with the hips. Also try to make your timing less uniform, runs tend to look good when the arms and legs spend more time at the extremes and less time in the middle. I agree that the head rotation is a bit much and might look better if the head moved with the shoulders rather than against. Act the motion out yourself to get a feel for what would look right.