The human players in the video appear to be tasked with completing objectives, while the Necromorph players attempt to chew some throats. The humans get weapons from the singleplayer game and even retain the ability to slow enemies with the Stasis ability.
The video is embedded below for your enjoyment. I guess that's what the Left 4 Dead Hunter looks like without his hoodie. Come on, EA... that's pretty blatant.
BOOM video 6420