Video: 20 min behind-the-scenes of "The Avengers"

The film that cost $220 million and unites all American superheroes; "The Avengers" is expected to be the highest gross film of 2012. After the good reception of the world premiere that took place yesterday, Marvel Studios released 20 minute footage of behind-the-scenes for fans to see some of the grand action scenes of the film where Iron Man, The Hulk, Thor and Captain America are saving Earth from an alien invasion. "The Avengers" stars Robert Downey Jr., Scarlett Johansson, Mark Ruffalo, Samuel L. Jackson, Chris Evans and Chris Hemsworth and will hit theaters on 4 May.Watch behind-the-scenes in four videos: