So on top of releasing a launch trailer nowhere near the game's release date, Microsoft saw fit to release a second launch trailer for Halo 4. At this point, the only reason to call it a launch trailer is because it will presumably make you launch out of your chair with excitement.
This one actually has some gameplay in it, and its structure and length makes it perfect for a TV commercial. The tagline "An Ancient Evil Awakens" appears once again. No, it's not referring to Microsoft or the franchise itself, as much as some people want it to; it's referring to the Prometheans, the new race of enemies that Master Chief will have to contend with.