I have noticed that soooooo many people jump ahead and just over jump jumps!! (i'm still getting out of the habit myself). Especially in my lessons. My instructer keeps telling what they have to do to fix it but no-one seems to listen. I finally understood the whole "letting the horse close ur hip angle" thing and yesterdays lesson was my best ever! :) my mum took videos and I noticed a BIG difference from my previous videos and i'm soo happy!
I've also noticed on a popular website here in finland (irc-galleria) where you post pics that lots of people who had jumping pics had the kind of form the OP posted. Lying on the horses neck/jumping ahead/over-jumping. :/