The commentary from Redmond was illuminating for me, in his estimation having played against monte carlo simulations before, at that point the computer just plays very low probability moves with extremely high outcomes if the other player makes a grievous mistake. So the moves looked terrible since the 'retort' is obvious, but if for some reason LSD didn't play the obvious counter, it would catapult Alphago back into the lead. Of course since LSD is an expert, he never missed the retort, but very interesting behavior nonetheless.

I was hoping Lee Sedol would be able to at least win one, humans can 'learn fast'. We cant learn 24/7 in parallel like a computer, but we do seem to have quite the talent at learning 'situational' things very quickly, quite likely because our very survival depended on it in the deep distant past. :-)

I don't believe AlphaGo had the time to do any additional training between matches. So effectively Lee has the ability to 'learn his opponent' while AlphaGo cannot until the entire match set is over because of how long it would take do do additional training.