Robert Downey Jr on the enduring appeal of Marvel

The latest eagerly awaited comic book adaptation from the Marvel Cinematic Universe, The Avengers: Age of Ultron, is widely expected to outperform the first Avengers movie which took more than $1bn worldwide.

It will almost certainly make enough at the box office to ensure the film series overtakes Harry Potter to become the most successful cinema franchise of all time.

Our entertainment correspondent Lizo Mzimba has been talking to Robert Downey Jr, who plays Tony Stark/Iron Man, about the franchise's enduring appeal.

Clips courtesy of Walt Disney Studios.