It opened with a scene of Prince Noctis that may have been in or resembled Japan on a freeway. The next scene showed Noctis and a beautiful blonde as described by 4gamer (I believe this may be Stella) talking about how they can see the "light." Then a man in a suit said, "I’m sorry to say you cannot become the king. The crown won’t be handed over to just anyone. I will be remembered in history as the final king."
The trailer then cut to gameplay footage where a fight took place between a character (Noctis?) wielding a sword and battling a swarm of soldiers. A gigantic behemoth showed and the fight continued. Many more common monsters came out. Later, there was a scene where a character (it isn’t clear if this is Noctis) boarded a tank and controlled it. A two legged robot was shown too.
Final Fantasy Versus XIII, as mentioned many times, is for PlayStation 3 only.
You’ll be able to see this trailer and others from the Production 1 press conference on January 27.
Update: Pictures of the mysterious man in the suit who makes the king comment and some gameplay screenshots. Regarding the quote, it appears the "suit character" is being merciful with his decision to end the linage. Text, in English, read "an act of love by the last king."
Bits of gameplay showed Noctis running away from an exploding building. There were no transitions into fights. Noctis ran into armored soldiers and attacked them with two other characters. It appears players can switch characters in Final Fantasy Versus XIII. During battles, the trailer showed glimpses of magic like a lightning spell and a fire attack.
Noctis can commandeer vehicles. He took control of a turret on a tank and a two legged robot in the video.