If you're just visiting us from another planet, the shooting of Trayvon Martin is the famous case recreated in this PSA. The rain, the 911 calls, the dark streets and the hoodie are all there, until the end when the camera pans out to reveal the twist.
This ad wants you to Stand up to stand your ground, to tell legislators to change the law. To quote their page "the laws represent a dangerous and unprecedented escalation in the use of force in the public space". The ad is paid for by The Coalition to Stop Gun Violence and will run sporadically. It'll probably garner a lot more attention on the web, considering the scenario it chose to depict as the "stand your ground law" was not used by the Zimmerman defense team during the trial.