THE MOST PROMISING young entertainers aren’t on TV or in the movies. They’re on Youtube, fronting their own channels with videos attracting billions of views. The ten celebrities on our list of the top-earning Youtube stars earned a total of $70.5 million in the 12 months ending in June, mostly from advertising and sponsorships, a 23% increase from a year ago. They’re a diverse lot: a musician, a prankster, a nerdy baker and a couple pseudonymous gamers. No. 1 again was Pewdiepie, who turned silly snippets of himself playing videogames into a $15 million paycheck, a 20% rise.