You landed dangerously close to the box. Closer than you realize, because if you "make a mistake" and have a worse vault than what your vid shows, then you'll land in the box. Worse yet, you're in danger of landing in the box FACING THE WRONG DIRECTION!
Lower your grip by 8", making sure that you land well into the pit - about 2-3 feet more into the pit than this vid. You'll have to move your standards back quite a bit more, but that's a good thing.
This will give you a lot more room (and time) to swing your trail leg up and land on your back.
You need to practice this without a bar - not even a bungee. Don't put up a bar until the next meet - it's distracting you from learning proper vaulting technique.
Don't worry if you don't get as much bend - you don't need it yet. That will come later, once your technique improves.
Once you're good with a 12-4 grip, then you can move it up to 12-8, but after that your technique will have improved to the point that you'll have to use a stiffer pole. (These grips are just approximate - your mileage may vary.)
There's quite a few other things you can do, but lowering your grip and getting a good, reliable, safe swing tops my list of hints to you right now.
You're going to be a good vaulter if you stick with it. Just don't expect to build Rome in a day. And practice, practice, practice your swing on a highbar!
I hope you have a coach. If you do, listen to him - not to me.
Kirk Bryde