I have heard the information was released because a made for TV production going into the (up until recently, secret) details will be aired very soon, and the government wanted to take some of the wind out of its sails with a preemptive release of some (of the lamest and crappiest) of their UFO videos. I suspect this is just another small step toward disclosure and that the plan is to very slowly and gradually desensitize the world to the idea of aliens but to eventually use their existence to justify a one world government...