Those aren't just regular folks in funny clothes, and this is one of those harder-than-it-actually-looks kind of things. Those are the stunt actors of Film Fighting LA swinging swords around, doing an Assassin's Creed send-up. This was filmed in one day and with barely any rehearsal, and it kinda shows it. On a side note! Film Fighting LA's Robert Goodwin (dude in the chain metal) trained Christian Bale in martial arts for Batman Begins, and that movie was pretty bad ass.
Oh, you might want to watch the clip on mute. Trust me.