The digital music revolution started with Napster – the file-sharing service dreamt up by two teenagers in 1999. As a new film tells Napster's story, Tom Lamont recalls the incredible sense of liberation he felt as a young music fan, one of millions happily plundering the world's record collections…

In the first weeks of 2000 the founders of Napster were in their office above a bank in San Mateo, California, considering dizzying numbers. Figures scrawled on a whiteboard told how many people around the world had installed their file-sharing application and were using it to download music from each other's computers. As recounted in Downloaded – a documentary soon to premiere at the SXSW film festival, telling the story of a piece of software that came and went and whipped up a new digital music industry in its slip – Napster had 20 million users at the time. Some way from San Mateo, in suburban London...