i also watched the whole thing. about 45 seconds into it, i really wanted to shut it off, but i endured.
i once read about a study that was done which concluded that 82% of teen girls get a slight "rush" out of hearing their own voice, and for some (the ones most affected,) the sound of their own voice combined with the high speed at which they speak can give them the excitement and rush that can only be compared to crack cocaine.
i thought it was hilarious, and, having a sister who is just like this, it now makes complete sense why she would talk so fast like that.