(I didn't see if anyone mentioned this, but...)
In the video the character is "Square Enix", right?
The other characters are "Gamescom [Eins/Zwei/Drei]" (aka 1,2,3 en Deutsche)
So I think that someone behind the scenes was doing the Square Enix footage live as Yoshi-P was talking, following some basic "lines", and the other characters were probably players trying it out in the SE booth, where the booth reps would ask them to cooperate with the main character. That's why they'd get the video /first/, it's Live, not pre-scripted, which...personally, I appreciate more. It's truly showing off the game to anyone who can see it, and thanks to the cameraman, we got to (early).