that their shorting of the market meant that they could take a big beating on their futures and still make a lot of money... with their short on, they wanted to see the price drop precipitously. Also, (this is for you box) this is a case of a paper created shortage and glut, not an actual shortage or glut beyond what physical inventory's actually there.
I mean, it's not like this has caused the price of gas to fall a whole lot, now has it? That makes sense when you think about it, because the actual physical amount of oil changed by not one drop as a result of this market manipulation.