Via CSN Philly, a couple of videos of Eagles fans pummeling the hell out of Eagles fans:
CSN's Enrico Campitelli was sitting near this fight, but couldn't tell what started it. He did note that the most injured party was the poor guy who got landed on.
While many of the brawlers were hit in the face with force, an innocent bystander (mustache and sunglasses in the first video) received the worst of it when two men literally came flying down multiple rows of seats on top of him and crashing him into the seats. The initial thought among the crowd was some broken ribs.
The second video gives a better look at some of the combatants, and if someone forced you to guess which two Eagles uniforms would be worn by two guys punching each other in the stands, you probably would've nailed it: a Riley Cooper and a guy with a personalized No. 69 jersey.
In conclusion: attending NFL games is a terrible thing to do.