its a trailer...got it, a trailer, a short video used to get your attention.
it may not be accurate to the story of halo, or the other halo games.
so please, can we all just stop picking it apart for inaccuracy already, just watch it, enjoy it, and get excited about the game that is to come.
I'm sure ES and Bungie will solve all the story contradictories by time the game hits the shelves.