What ‘Serial’-mania says about the popularity of podcasts

A weekly podcast has riveted millions with its exploration of a true crime story and its questions about whether the man at its center is guilty or innocent. "Serial" probes the 1999 conviction of a high school senior who was charged with the murder of his ex-girlfriend. Hari Sreenivasan talks to Slate’s David Haglund about the runaway success of the show, now the most popular podcast in history.