I can do every Barrel Roll except the last one on the bridge part. Youtube doesn't help that much, i'd like a good solid description please =]

yeah that one is a hard roll to get...
u really have to go far right like very close to the edge of the track and at the last second u go left...
so ur barrel roll should be Left right Left
but dont give up
I had a real tough time to get it but one day it just got threw and finally beat him

good luck