Ask questions before... and perhaps don't agree to play this game otherwise. A real Sales professional really can't present a 15 minute sales demo without process that includes discovery or qualified pipeline. Most wouldn't even travel to demo unqualified deals. You need to ask questions, because you won't have that history from working your pipeline and they will not have the contextual information to engage your industries sales context to bridge the gap. Hopefully this exercise will have been refined in the future.