OK,by the time you read mine someone would have pointed it out to you. YOU are riding stiff! I can see your knees are bent but, your whole body is rigid. Relax, loosen up on your turns by initiating with your front foot with a slight lean forward and your knees and pushing your shin into your boot. put your hands down, keep them to your side as much as possible. Heelside turns is a bit ehhh too The biggest problem i saw on your vid is when you turn to your toe side(facing uphill), your heeledge is so close to catch an edge because you do not have enough angle on your toe edge. One lazy turn and you'd smack your noggin backwards! I did mention that your knees are bent but you need them to be loose as well to absorb bumps and initiating turn will be easier. Keep riding and stay relax.
2011 Ride Antic 163
2011 Status Focus 158