EPTI happened to tune in on that particular set and immediately started squeeing in fanboy glee. Games like this are why I love watching pro Broodwar. So what happened? How did a relative B-teamer manage to beat Bisu?
The short answer is 2fac, but a lot more went into the build that Sin used. The first thing that struck me was the mindgame he pulled on Bisu--from the outside in, it looked like Sin was using a standard FD, or Fake Double. I think it was Midas who popularized this build some time ago--2005? Anyway, for those who don't know, FD is so named because it creates the illusion that Terran is going for a double factory push, leading the Protoss into believing that the victory is now predicated on stopping the push. As it turns out, the aggression is actually a screen for the Terran to take his natural. Much more detailed information at the liquipeda page.
So what does an FD look like? In the past, it used to be around 4 marines, a siege tank, and a vulture at the outset. The marines and tank would provide the DPS while the vulture would constantly contest position by planting mines around the Protoss' defending dragoons. Good micro would chase the Protoss all the way to his natural, where the Terran could choose to continue his aggression. The build is most effective against greedy builds that delay observers for whatever end.
So this is what Bisu saw when he scouted Sin--or at least tried to, since Sin had four marines to block the scout. This is perfectly reasonable, and he could still continue his assumption even after Sin sat at his natural choke. One tank, eight or so marines (or was it? I can't find the VOD yet) and one vulture--perfectly standard modern FD. Bisu only realized something was up when far more vultures were out on the field than were possible with just one factory. I wish they zoomed in on his face when he had a bunch of vultures running around his side of the map. Bisuface 2.0? Nah, probably not.
Anyway, what followed was a late response to a 2fac. From the Terran point of view, a 2fac ideally will kill the Protoss outright at the first engagement, but that only happens with D players on iCCup. The Terran will know to move to set up a hard contain, complete with buildings and all kinds of Terran ridiculousness in front of the Protoss natural. Which is exactly what Sin did--he immediately started an engie bay and a bunker, along with a supply depot if I remember correctly.
This made me realize how well-thought out this build was. Let's look at this from the Protoss' point of view: Tanks and shit in the natural, what do you do? 1. Try to break the contain, 2. Sac the natural and break the contain later and 3. Take advantage of the Terran's all-in to do some reaver or DT harass in his main, hopefully crippling his economy badly enough that you can break his contain and still come out even, or more likely on top.
All of this involves shuttle play, as the commentators immediately pointed out. So the engiebay and the bunker made sense, except they were late. Sin messed up and left his marines in his main, turrets don't build in ten seconds, so Bisu broke the first contain.
The rest of the game didn't have as many "oh man that was cool" moments. There was the fast +1 that Sin got that made a lot of sense, given that he was, you know, all-in; a lot of ridiculously intense engagements; Sin sniffing out Bisu's 3rd immediately, which was another sign of how well he'd prepared; getting a Goliath perfectly in time to stop Bisu's first counter-drop in his main; almost setting up a turret in time to stop Bisu's reaver drop...I guess these are the last few highlights I remember that wowed me and the commentators.
Hope this sheds some light on this set. I know it seems a lot like a stupid 2fac from an out-classed Terran, but it was actually a joy to watch if you saw the less obvious details.
