I did demo for several manufacturers including the Yamaha electones, Hammond organs and Lowrey,(remember those AOAI conventions in the 80's in USA?) said that, you need to have playing skills and showcase the instrument you are demoing, there are basically 2 types of demos, one that show to the users/customers/salespeople, what is available in the instrument, styles/features can sound like, the other, is to "show-off" not just your skills, but the instrument as well. One of the masters is Hector Olivera(now with Roland Ataliers) that did demo for Yamaha the HX1, also made a software company with a very young talented Craig Knudsen, they made sounds, registrations, etc, and the "Freeze" floppy for the MDRs that where used on the Electones at the time.

And as far it goes, in the Clavinova/T2 video demo, using a SMF, as well a style (In a way a style is many midi files that loop in a controlled/manipulated way), it is consider Real time, because it is happening in that precise moment.

Like I said, I have used and still use similar "stuff" to demo/perform, I prefer use styles, actually, User styles/song-styles, etc...
That way you sound like that(showy), without the limitation that the SMF has, the duration, this way I can make it 2 minutes long or IF I wish, 15 minutes long, wherever I feel like.

I have nothing against using SMF, I use the ones I make myself, there are partial, meaning, it does not have ALL the parts, I purposely left the parts I play live along with it.