DO NOT BEAT AROUND THE BUSH. Do not hem and haw. "Uhm"s and "uh"s don't lend an aura of intelligence.
Use precise and concise language. You aren't pitching a VC that will ask you what your "secret sauce" is.
He talks quickly, and so do the other YC partners. Try to match their tempo (as you should when talking to anyone).
Obviously someone with a solid business plan who speaks cautiously is in a much better position than a smooth talker who is selling vaporware. That's the value of the YC group, they have their priorities determined and they don't get taken for a ride.
For must formal presentations the audience expect clear and concise responses. One should be forgiven for "filling" during a public speech or informal chat.
That's stupid advice. Why should I always match my tempo to somebody else?
I'm not going to adapt to your talking speed for the same reason that you're probably not going to try to match mine. I'm not your monkey.
http://lifehacker.com/5894462/use-mirroring-and-matching-to-...
Because it's an important element of building rapport. And rapport is important if you want to get someone on "your side" in a discussion.
for the same reason that you're probably not going to try to match mine
But people usually do just that. It's a fairly well established thing, that people in a conversation usually eventually match each other's talking pace. And it generally feels awkward when you're talking to someone and that doesn't happen.