We're gonna get a short 30 second video of FFXIV characters animated to Kriss Kross' Jump.

all races will be shown jumping around with the Large font bolded text flashing into existance 1 by 1 :

R
U
HAPPY
NOW!?

then a slow fade in:

FFXIV 2.0: now with jump.

In all seriousness, I think we'll see a CGI type movie of the event leading into the 7th umbral era. aka Meteor smashing down in eorzea followed by a montage of quick cuts of in game footage. nothing lasting more than 2 or 3 minutes tops.

Unfortunatly SE will miss their chance to impress the gaming world/press in large at this event. Maybe it's for the better as other compnaies will be showing their big guns as well. SE might be saving the megatonne for vanafest which is a week after E3 or tokyo game show which isn't far off either to have a more intimate unveiling of FFXIV to try and draw more attention.