Firth: 'Mamma Mia' one of my best films

Colin Firth believes starring in 'Mamma Mia' is one of the "best things" he has ever done.

The British actor – who has won the Best Actor awards at both the Golden Globes and the BAFTAs this year for his role as King George IV in 'The King's Speech' – explained while people expect him to be ashamed of his all-singing, all-dancing role in the musical film, he counts it as one of his biggest achievements.