i believe your problem is two-fold, but the main technical reason is this:
- you're not completing your roll.
you may feel like you are, but you're not coming down with your weight over your board. to illustrate, take a look at these two sequences (one done right after the other), of me doing first a successful backroll, albeit low, and then a higher, but non-successful backroll because i don't land with my weight over my board.
if you freeze frame your video you'll see how much like the second one of these it is...
first the successful one:
see how im landing with my weight over the board? so much so that i slide it quite a bit before recovering.
now the unsuccessful one (which i took higher, but didn't rotate as fast):
notice how the weight is back and i end up crashing backwards (compare the shoulder position in the 3rd pics of each sequence). this is where having both hands on the handle would help. i probably could have pulled this out if i'd kept my trailing hand on the handle.
the second idea is that i think you're a bit head-tripped by this. you bounced that landing like you weren't ready for it. it's almost as if you don't expect to be able to land.
your form is perfect until you hit the water. you just need to commit a bit more to the roll. as you're coming down you need to get your shoulders a bit more forward. as david said, this is where spotting your landing may help - but if you can do that you're way ahead of me. i've been doing backrolls (albeit inconsistently as you can see from this sequence!), for about a year and i still don't spot the water most times.
good luck! let us know when you get it or if you need more help.
edit=got the descriptions backwards!
(Message edited by deepstructure on August 19, 2003)