From what I've read it doesn't matter too much, it seems like:<p>1) they'll read through applications
2) if the application looks promising look at the video
3) if the video isn't bad look at the demo<p>I'm guessing that most of the time they look at the demo they've already mostly decided whether to interview you or not.<p>(If you don't have any past proof of being able to build things, etc. it might be more important though)<p>I've seen several people say that when they were at the interview stage the YC partners mostly ignored the demo and focused on questioning.