Fortunately, he wrote a whole essay on that very subject: http://paulgraham.com/founders.html . It's the fourth from the top on his "Essays" page: http://paulgraham.com/articles.html .

I felt he deliberately did not go into this topic. He was asked "How do you pick ~60 out of ~2000 applications?", and his entire response could be paraphrased as "We have practice". It made me wonder if it was because he thought it was too complex a topic for a quick TV show.

I wrote about how I read applications here:

http://ycombinator.com/howtoapply.html

http://news.ycombinator.com/item?id=801739

I wasn't suggesting that you were unwilling to divulge this information. I meant that I felt you did not wish to discuss it in that forum.

Semi-related: The YC application for Dropbox from the link above seems to have been taken down.

Does anyone have a mirror?

Thanks Paul.