It does seem rather odd that they'd sort of "tease" this co-op concept without implementing it in some form or fashion. That brief clip is fairly contextual...lady goes on to say "what is this? co-op? Then you join the arena where 6 others are waiting which is an important way to introduce the multiplayer..." (paraphrased)
Still it makes one wonder if that bit of a tease will be foolishly overlooked by the developers...Co-op is a huge and largely untapped arena in multiplayer gaming. It's scary to think that we've ZERO about a potential co-op mode in this game...but SSM has managed to stay hush-hush about the ENTIRE game for the entirety of its development so hopefully this is just that one last reveal waiting to happen to throw everyone's excitement into a fever pitch before release...?
Omg Co-op would easily get this game game of the year. its just to danm good at that point. Multiplayer, Online Co-op survivor, and epic single player and nothing will touch this game. That footage easily shows that it is possible.
I dont think that video was showing coop, if u hear correctly she starts off by saying it makes u think your in single player and then someone jumps in so you think its a coop game, but then after you beat the boss you go into the main arena where 6 other people are waiting for u. I think that was just made up for the big launch announcment for people who were involved in watching the actual game play. It was just to throw them off of what to think. But lets keep our fingers crossed and hope the last mode is coop.
I really do wish there is co-op. Like Tank_610 said another multiplayer game mode is just a variation of "kill people". Team favor is pretty much Domination and King of the Hill combined, or seperated depending on the maps. Co-Op would indeed be awesome.
On a side note, some of the dev videos pretty much confirmed AI grunts (Satyrs, Gorgons, etc) in multiplayer. Whether this means an actual co-op mode or just AI in the maps is something we'll have to wait to find out.
HOWEVER, based on the footage it seems that the secret mode is a co-op/versus hybrid where you can't directly kill your opponents but use the environment to prevent them from completing the objective, which is to kill as many monsters as possible.