What really matters is your determination and team. A few hundred words hardly puts them in a position to provide you valuable feedback on those factors.
Sure, other things matter more, but getting feedback certainly wouldn't hurt. Especially feedback coming from YC, because I respect their opinion and tend to think they know what they are talking about.
And, obviously, if I got feedback, I could always ignore it and be in the same position as I am now. I'd rather have more information than less.
A rejection doesn't mean there was anything wrong with your application / start-up / you personally at all.
All it means is that there were other start-ups that caught their attention more.
You have to remember that they look at this as a business process, and a huge part of that process is "can we make money off of this as well"; it's tough to ascertain that over a video.
Keep on trucking, and I'm sure you'll do fine. It's 90% perspiration anyways.
Feedback wouldn't necessarily be very useful. The feedback might be a meaningless number such as '42' in the Hitch Hikers Guide to the Galaxy Deep Thought (which doesn't really explain the result of the question).
What really matters is your determination and team. A few hundred words hardly puts them in a position to provide you valuable feedback on those factors.