Butterfly Help/Video Analysis

We had a videotaping session in practice on Wed and I got some video of my butterfly. I've been trying to work on my butterfly lately but I could really use some pointers and suggestions for specific things to work on and how to work on them. Clearly the turnover is too slow. Lack of range of motion in my shoulders doesn't allow me to keep my hands at the surface while my chest is down the way that people like Phelps do. In the underwater side view it looks like my hips sink way too much and then don't quite make it back up to the surface, but I don't know what to do about that other than a quicker recovery. youtube.com/watch Thanks in advance for any suggestions!