Multiplayer is where you play GEFS with other pilots in the world. You have callsigns like Foo a not logged in person. A video of the MD-11 crosswind landing with Multplayer.
As of Multiplayer you can fly and chat allover the world as of this Airbus A380 seen here flying over Boston.
GEFS Online MD-11 Crosswind Landing On 04R At Nice HD
MD-11 landing on 04R at Nice with multiplayer