The mode in play is Defuse, a five versus five mode in which you transport a bomb to the other side's base. I spoke to DICE's Lars Gustavsson about Flooded after tackling the multiplayer for the first time in August - apparently, you can destroy the levee to drown the whole area. Vehicle drop spots will then switch over to dispensing boats. Pretty neat.
Given that Defuse is one of the more intimate modes, it's likely you can't see the map's entirety in the video - when I participated in a round of the similarly small-scale Domination on Paracel Storm, I was confined to one of the map's islands. This is the PC version, obviously - for offscreen footage of the game in action on Xbox One, click this.
Battlefield 4 is out on 29th October for Xbox 360, PS3 and PC. It hits Xbox One on 22nd November, when the console itself goes on sale. There will be 10 maps and seven modes at launch.