Well, if it's an exclusive extended gameplay demo, doesn't that imply that there'll also be a non-extended demo?
Possibly. Or they just added "extended" to make it sound more special. Given that E3 is about a month away and Square has a marketing deal with MS, I just find it highly unlikely that they'd debut a gameplay demo to the general public right now. Seems much more likely that the demo would be saved for the MS conference.