Nigeria abduction video: Schoolgirls 'recognised'

Relatives and friends of a group of Nigerian schoolgirls abducted by Boko Haram have identified them from a video released by the Islamist group.

The footage showed about 130 of more than 200 girls who were kidnapped a month ago from their boarding school in Borno state.

Meanwhile, the US has revealed it is flying manned surveillance missions over Nigeria to an effort to find the missing schoolgirls.

John Simpson reports.