It's certainly a gamble - our (successful) YC application took a couple of days to put together, partly because the video was a real pain to get right.

That said, answering the questions in the application form really is a very useful exercise whether or not you make it in - it made us think about our company in a bunch of ways that we hadn't necessarily considered before we started applying. That's the difference between a YC app and the lottery - a lottery ticket isn't going to teach you anything.