About the only analysis I can offer is this play is the hockey equivalent to the circus jamming 50 clowns into a tiny car. The clowns are the players piling into the crease, and the car is the crease.
Just look at this chaos.
So many things happening here. Tomas Vokoun, the goalie, is one of the few players not actually in the crease. Penguins defenseman Kris Letang appears to block one of the initial shots with his face, and then ends up in the back of the net after getting away with covering the puck in the crease. Vokoun ends up flat on the ice with a Flyer on top of him and after just about every player on the ice gets a touch of the puck Grossman finally deposits it in the back of the net.