After we beat the game, we now know that in the Bioshock universe there are an infinite about of universes where every different outcome is explored. If you go back and watch past Bioshock Infinite videos from a couple years ago it looks like a completly different game. I read in an interview with Ken Levine that they had enough material for several games. Maybe the preview videos are clips from different universes. These different universes could be plots for the new DLC that is supposed to come out.