The social giant suffers one of its worst ever weeks after a tech blunder takes its platforms offline for hours, and a whistleblower gives highly critical testimony to Congress about its attitude to online harm. Plus, the CEO of cryptocurrency exchange Binance tells us why he’s convinced digital currencies are the future of finance. And why is China clamping down on cryptocurrencies? Presented by Rory Cellan-Jones, with BBC tech reporter David Molloy. Produced by Jat Gill.