This hairstyle is borrowed from the fabulous Mindy over at Adopt A Do and she calls it the Bubble Braid.
It is super fast and she's got a great video there as well.
I did mine a little differently because of a time crunch. Instead of ratting the hair I just placed the elastic in and pulled at it a bit.
It seemed to hold fine so that is an idea if you are REALLY short on time like we were. :)
It's a fun idea and she's got lots more great ones over on her website!