Well keep at it yo! Best 2 ways to improve is to watch other well made AMVs and to keep constantly editing.
Anyway this video has more value for the editor than for the viewer, or at least a cynical angry viewer like me, since its all about 1 single battle and the same editing/overlays throughout the whole short thing so one can barely notice when you do anything.
But don't be discouraged, keep going yo, Vegas is a good step towards improvement.