Feyenoord's Miguel Nelom chucked the throw-in toward the center of the box. It missed a crush of players, bounced over the goalie's head, and went into the goal.
You can't score a goal directly from a throw-in. The referee ruled that the throw hit Feyenoord's Sven van Beek, but on replay it's unclear if anyone gets a touch on it.
It looks like he just threw it right on in (via Who Ate All The Pies):