First he makes a lot of sentry then he forms a giant eclipse around the terran bio using forcefields to push them together into a ball and then puts a force field in the middle of it which splits about 15 units into 2 tiny clumps the size of the Collosus aoe. At first I wasn't completely sure if he clumped them into 2 holes on purpose but he does it again later in the game and when I rewatched it and then watched the first game where he does the same thing except he changes the size of the hole to the size of storm so I'm positive he's pushing bio into a ball for aoe.
I've seen this type of mass forcefield play recently from Huk where you don't just use forcefields to trap an enemy in or keep an enemy choked off but to actually completely surround and immobilize an enemy. However, pushing units together and using Collosus and Templar really take it to a whole new level since aoe completely destroys units that have been stuck on top of each other. I think this sort of Doughnut Hole micro will catch on more in the months to come.
A link to the match.