While watching the video I think it has something to do with that last ODST pod coming down from space. You noticed after all the other pods where blown away this one pod starts coming from the sky (47 secs) and crashing down onto the camera. I believe that's where we would start from that point. I can't wait for this to come out.
I hope this would bring us to the fight in the city like the monument museum large scale battles with ODST and Marines.