"Avengers: Doomsday" trailer: Doom's Sentinels face the Avengers and X-Men

Marvel Studios unveiled the second trailer for "Avengers: Doomsday" at Disney's D23 convention. Robert Downey Jr.'s Doctor Doom commands an army of Sentinels against both the Avengers and the X-Men. The film opens in cinemas on December 18 and was introduced by Downey Jr., Chris Evans and Hayley Atwell.