Why Facebook's in trouble again

Facebook is hauled over the coals by US congress on a semi regular basis, but this week has been especially damaging. Former employee Frances Haugen has blown the whistle on the company, leaking internal documents that reveal that it knew it was harming its users. Today on The Signal, what exactly has Facebook been keeping from the world? And what does the company have to say for itself? Featured: Siva Vaidyanathan, Professor of Media Studies, University of Virginia, US