FF-XIII.net has enhanced the audio and converted the Final Fantasy XIII trailers to MP4 and to HD resolutions 1080p and 720p, viewable on your computer and PS3. 480p and PSP resolution versions of the enhanced trailers are also available.
Due to FF-XIII.net being down you can find the 1080p HD Trailers here.
Second Update: The second trailer there has been updated to the original file from FF-XIII.net. The Original Versus file is coming.
Third Update: The first trailer, the Versus trailer, has been updated to the original file from FF-XIII.net.