A fan who saw the video has written what was the video about! The following text contains major spoilers from the upcoming Marvel movie Avengers: Age of Ultron.
First it starts out at a party. Tony (Robert Downey Jr) tries to lift Mjolnir and fails. Then Bruce (Mark Ruffalo) does and also fails and Maria Hill (Cobie Smulders) jumps thinking he’ll hulk out. Then Tony tries with his armored arm and fails. Then he tries with Rhodey (Don Cheadle) and fails. Then Steve (Chris Evans) tries and barely moves it. Then Thor (Chris Hemsworth) makes a joke about not being worthy and picks it up and flips it. Then Ultron (James Spader) crashes the party with his bots. Then it shows the hulkbuster armor and Bruce in the snow. Then it shows Black Widow (Scarlett Johansson) and Hulk’s hands touching in a romantic way. At the end it showed Steve’s shield completely destroyed and him possibly dead and battered. It also showed Loki’s scepter at one point.