"The Avengers" "Robert Downey Jr" "Iron Man" "Tony Stark" "Chris Evans" "Captain America" "Chris Hemsworth" "Thor" "Mark Ruffalo" "Hulk" "Samuel L. Jackson" "Nick Fury" "Scarlett Johannson" "Black Widow" "Tom Hiddleston" "Loki" "Cobie Smulders" "Maria Hill" "Clark Gregg" "Agent Phil Coulson" director "Joss Whedon" clip scene trailer extra scene credits ending interview cast