I rewound it a few times and pause it to so I'd say my opinion carries a lot of weight. I think the pop he hear was the suction from Sean Payton removing his asshole puckered lips from Bree's backside.
I looked on google and it said you usually don't hear a popping sound from PCL injuries so it might be an ACL strain. The fact that he had the mobility to go back out there tells me it wasn't torn. Hopefully he'll be ok by the playoffs.
I'm also staying at a Holiday Inn Express tonight so I'll probably have some more details tomorrow. (If they have an internet connection to WebMD)