It's a perfectly designed fake punt, and one that came to light on the previous series. The Steelers were lined up to punt the prior possession, and the team spread out on the field, only to come back to the line. Everyone except gunner Antwon Blake, who stayed on the outside. The Browns didn't cover him, thus giving the Steelers the knowledge a fake would be open if they needed it.
They would, and it worked perfectly. It was the Steelers' longest gain in an otherwise dreadful, second-half offensive performance. Considering the Steelers were at their own 20-yard line when the play was called, the only reasonable explanation is special teams coordinator Danny Smith gave Mike Tomlin a 100-percent guarantee it would work.
A few key points to note in the play. First, it's unclear what exactly Cleveland's strategy is. Rookie cornerback Justin Gilbert appears to be the player responsible for the gunner, and he's intentionally lined up on the edge, as if to show he may rush the punt. He breaks immediately back to cut off Blake's angle, seemingly unaware of the throw until the ball was in the air. He approaches Blake off-balance (something similar to what he did when Justin Brown was flagged for pushing off) and whiffs on the tackle. Brown made contact but Gilbert so badly over-pursued Brown's route, when he broke outside, it looked as if Brown tossed him downfield.
It's a great athletic play by Blake to secure the catch before looking upfield for more yards, but he's got some pretty decent moves too. He swipes around the technically inferior Gilbert (remember when we ripped him for this before the draft? Training camp didn't improve it.) and pushes upfield for a 25-yard gain on an 11-yard throw.
As for the throw itself (insert your own Landry Jones joke here), Golden gets the snap and grips it just tight enough to deliver an on-target throw, more or less. Very difficult on such a hugely important chain of motion. An impressive job all-around from the Steelers' special teams.
Now, if only the offense had capitalized on that drive, but that's another argument.