Ground Zeroes is a prologue to Metal Gear Solid 5, Kojima said at the event. As you can see, it looks pretty damn good.
Enjoy the video.
[Update] Here is another video, this one from IGN, showing additional gameplay footage, with voice-over commentary and translation.
Note: This story's original headline called the footage "gameplay." While it's true that a Metal Gear Solid game's gameplay mostly involves watching people talk, we've changed it to "in-game footage" to be as accurate as possible.