Zuckerberg to make it harder for app developers to harvest information in future.
We hear from an early investor in Facebook and mentor to Mr Zuckerberg.
Also in the programme: over 100 girls abducted by Boko Haram in Nigeria come home
And a silent movie that predicted the Nazis is found and restored.
(Photo: Mark Zuckerberg speaking at Facebook headquarters. Credit: EPA/PETER DASILVA). Show less