US artist John Mayer has unveiled his latest web wheeze – an augmented reality video for his song Heartbreak Warfare. Fans can turn on their webcam and hold up a printed or mobile version of a special icon, which triggers the video to start playing with themselves in the background as an extra. It’s being hailed as the first AR music video, although Los Valentinos have just done one too, while in August this year Sean Kingston launched an AR karaoke site, which got fans to sing along to one of his songs with an animated version of the star dancing around them.