Jake Paul, KSI, PewDiePie and Zoella are mega-stars to the young and a mystery to the old. As YouTubers, they influence the views, lives and purchases of millions of fans. And their power is growing:
Two billion people now watch YouTube, yet its stars are a mystery to the general public and media. What is the secret of their appeal? How do they cope with being in front of the lens? And who is behi
