World in Progress: Who's going to succeed Ban Ki-moon?

The top job is up for grabs at the end of this year, when UN Secretary-General Ban Ki-moon's term runs out. The election process is usually shrouded in secrecy - it's often decided behind closed doors who will take over. But this time, the UN is trying something new: Giving candidates a chance to make their case in public - and giving the public the chance to ask questions.