Square Enix is probably one of the best developers ever known, especially when it comes to keeping trailers from the public(!).
SE released about four Final Fantasy XIII trailer in their closed-theaters, but they have only showed one to public - if you don't count the extended CLOUD trailer of course.
At the Tokyo Game Show, which was held in September this year, Square Enix showed the first ever Star Ocean IV trailer. Of course, yet again, in their famous or rather infamous closed theater. Well now the trailer finally hit Youtube, you can watch it right here:
Star Ocean IV is now planned for one of the nextgen platforms. Square Enix has yet to announce for which it is yet, but we'll let you know as soon as we can.