It seems to me that the pitch is in the application anyway. I can't imagine why they'd want you to just repeat yourselves.

You shouldn't expect them to remember what was in the application. If they do remember something it will probably only be one line.

That actually goes for investors in general, from what I can tell. Biggest mistake we made with the first investor that invited us in was assuming that he knew what we did. (One of his associates apparently had said that he should talk to us; he'd never looked at our website.)

In the case of YC interviews, that paragraph that says what your company does is buried in the thousands of pages of text that are going across their eyes during the screening process. Don't expect them to remember it verbatim. ;-)

Is a demo required?

I think its incredibly foolish to try to get funding for something that has no basis in reality yet. That's what a demo really is -- a toe-hold. But that toehold is usually enough to know whether a team can make it a reality, and whether they have a chance in the real world.

There's so much competition from great teams that it may well be a waste of time without showing your best.

I understand but Paul Graham really makes an emphasis on the team, and that a demo is not required. I mean there has to be a way to prove that that the team can produce what they claim: past work, past startups, etc right?

I think YC is sufficiently competitive that teams without a demo (on the application) will not even get an interview. Also (I believe it has been said), the two weeks from when you're notified to the weekend of the interview should be sufficient to produce some kind of early stage demo. Your startup idea might be unfit for YC if you can't at least have something to show in two weeks of fervent work.

Thanks for the advice. I was under the impression that the demo would be unimportant, and since I'm in school right now, I thought I'd go slow at it unless I am accepted.

I can whip up something in two weeks easy (even with school), but I didn't submit a demo in the application because I didn't think it would be necessary, so I focused on developing the idea instead.

Trevor talked about this in the comments to my article on applying to YC:

http://news.ycombinator.com/item?id=854088

I guess what my situation was that I could balance school and the application, or school and the prototype. While I had an urge to work on the prototype I always felt guilty because frankly the application has a deadline, the prototype does not. Actually after the application deadline I was able to get back to the prototype.

If you get an interview, unbalance school to get the prototype ready - 'don't worry be crappy' - for the interview.

Oh definitely. In fact I did that the last time I prototyped a site and not only was I not doing it for any investors, I had finals the same week.

No, but obviously better if you have one.