He's not nervous and he really knows his stuff for such a young fella. Ideally you would have a professional public speaker give these talks; problem is not too many of them have Ph.D.s in stellar astronomy.
Hope Mr Adrian Brown will be back soon to introduce our SETI talks Maybe one day he'll give us precious information about how you can write down so much information on the person you're introducting on such a tiny piece of paper :]
A question I may have asked, there's been some talk lately about the possibility of a "Nemesis" companion star to our sun causing 26 million year protuberances of the Oort cloud sending comets our way, unseen as yet, does one of these dark brown dwarfs have enough gravitational mass to be able to cause such an event, would it be big enough to hold this kind of long duration orbit, which could explain why it's not yet been found.
Usually, people who Umm and Ahh are very nervous speakers. As a professional speaker you learn NOT to or to avoid these words, which are usually injected to cover up gaps within speech. Even if the gap is only minor, many people feel the need to keep talking regardless, so they inject an Umm or Ahh to break any silence they feel will sound VERY evident instead of just allowing a small pause before speaking their next thought. Its not that hard to overcome with some training.
God knows I'm not in any position to critique anybody else's public speaking ability, bit this guy has got a terrible case of the "uh's". It makes his talk excruciating to listen to. I.f you can get past that, though, the.talk is really quite good.
