Those of you who are saying that that picture of the building from DD and ASAS is of Twilight Town at night you are wrong. Nomura said that some of the new features of the game would be the fact the the time of day would change from night to day in the majority of the worlds, however he also said that there would be certain places were the time of day would never change. Nomura gave an example of this and said that the place known as Twilight Town would be one of those places that would never change. This is because Twilight Town symbolizes the time, force, or area that is inbetween the light and the darkness. So Twilight Town will all ways be inbetween sunrise and sunset, and, or a never ending sunset, therfore Twilight Town has no night life and will never get dark unless something happens storywise to make it dark. Like the events that happend on the Islands when Sora first started this adventure.
As for the quality of the image of the dark city from DD. That is definitly not taken from DD and ASAS because it is not of FMV quality. Like New2Ya said it is of ingame graphics. And there was one picture were there was a bright light in the corner and Sora standing towards us. I also think that this is Sora fighting in the dark city which has yet been given a true name, but it could also be just an attack that makes everything temporarely dark.
Also I remember that not to long ago shortly after the events of E3 a gamefaqs forum member wrote a report about the KH2 trailer that was shown behind closed doors, the one that revealed PotC for the first time. In this report he had included the following,
"The last part of the trailer shows Sora, Donald, and Goofy in that dark city that was shown in DD and ASAS. They look puzzled when they are there. Then all of a sudden a black portal opens and an Unknown steps out of it(who happens to be about Sora's height I might add). He sends minions to fight Sora and Co., but I forgot if they were heartless or the white creatures. In any case, after they are dealt with, Sora and the Unknown exchange words(or at least thats what it looks like, again no voices or subtitles). Then they rush at each other, and the screen goes white.
Finally, a bunch of scenes fly by really quick, and the title comes out. There's a pause, followed by the beach scene from DD, and the this phrase comes out "If the world is made up of light and darkness, we shall be that darkness...." and then the trailer ends."
On the thread I started about this
http://forums.kingdomhearts2.net/showthread.php?t=17888 there were many of you who were sceptical about it and would say stuff like "It's just one guys report." "Don't you think the other game sites would of mentioned it in there reports aswell." Blah Blah Blah. Now this doesn't 100% prove that it was actually in the trailer shown, but it does give a 90% to 95% chance that it was indeed in the trailer. And As I said in that thread to those that were sceptical, "Like I said when posting this info some of it is unconfirmed, and by this I mean the newest stuff that the dude reported on. We can only wait till the trailer makes it's way to the net before we can assume to much of anythying. Besides some of the newest stuff might be true after all. This kind of reminds me of the time when many people did not believe some of the reports about the scenes in the jump festa trailer. then when the trailer hit the net they slowly slid to the edge of there seat's and let there jaws drop at the awsomeness of the jump festa trailer. I wouldn't be surprised if the same thing happened with this trailer."
It looks like everything is falling into place. Perhapse we will soon see that trailer aswell. This is one thing I cant wait for.