James Bamford - spying on the people who spy on us

Investigative journalist James Bamford started researching the little know US government department known as the National Security Agency in 1982. Since then he's written three books on the organisation which is now known for its mass surveillance of people around the globe. James tells us about how hard it was to gain information on the NSA back in the 80s, and whether NAS whistleblower Edward Snowdon is a hero or a villain.