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).
I wish they would have included some feedback.