What Facebook knows about you

The social giant will reveal what it knows about your internet activity off of its platform. Will its users appreciate the transparency or be horrified? Plus, Twitter and Google take down accounts indicating co-ordinated posting relating to the Hong Kong protests. How has that gone down in China? And, 3D printing was meant to democratise manufacturing. It hasn't quite worked out like that, but we see one example of a 3D printed consumer product - a new type of bike helmet. Presented by Rory Cellan-Jones, with BBC tech reporter Jane Wakefield, and special guest Isobel Asher Hamilton from Business Insider. (Image: Stock photo of a couple on a sofa making an online purchase on a tablet computer, Credit: Hispanolistic/ Getty Images).