Katy Perry chats about the story behind the "Firework" video

Katy Perry chats about the 'emotional experience' of her "Firework" video.

Earlier this year, Katy Perry asked fans in eight different European countries to star in her upcoming "Firework" video by submitting their 'spark' stories.

We get a look at some of the entrants' moving journeys.

"Firework" features on Katy Perry's latest release, Teenage Dream.