Islamic State: Peter Kassig's parents appeal for his release

The parents of US hostage Peter Kassig have appealed in a video to Islamic State (IS) militants to "show mercy" and release him.

Mr Kassig, 26, was threatened in an IS video released on Friday, which appears to show the beheading of British aid worker Alan Henning.

If confirmed, it will be the fourth murder of a western hostage by the militant group.

Alpa Patel reports.