China boasts the world's largest CCTV monitoring system with over 700 million cameras. In a demonstration, authorities located BBC reporter John Sudworth within seven minutes using facial recognition technology. https://t.co/pgjZcK5t8S https://video-cf.twimg.com/amplify_video/1826686135097085952/vid/avc1/1078x626/FB28iR1LoknrCChG.mp4?tag=16