This new trailer from CCP Games is a fine introduction to their free-to-play multiplayer FPS, Dust 514. It walks you through how your initial selections and preferences determines your eventual role on the battlefield. You'll make your own mercenary, picking your own skills, weapons and vehicles. All of your choices affects how the game will play out for you. And if your configuration sucks, and you die, you can just do it all over again!
Beyond the introductory stuff, this trailer gives you a quick look at how vehicles and team play work in the game, and also touches in its integration with Eve Online.
DUST 514 is currently in closed beta.