US election 2016: Why are young voters drawn to Bernie Sanders?

The American election campaign has taken an unexpected twist when it comes to young voters - most have rallied around Bernie Sanders, a 74-year-old white man promising revolution.

But would that youthful energy, swing behind Hilary Clinton if she beat him to the Democratic nomination? And who do young Republicans have, to get excited about?

Barbara Plett-Usher reports.