It's action packed and violent but hugely successful. The Grand Theft Auto franchise is a global phenomenon - and it's fifth game has just become the world's fastest selling. It earned $800 million on the first day - easily beating its main rival 'Call of Duty'. It's Take-Two Interactive Software's most lucrative franchise. But it's not made in the US - a tiny Scottish firm Rockstar North developed the video. James Binns says the industry is fast becoming one of Britain's best exports.