On stage today at Radio City Music Hall, YouTube CEO Susan Wojcicki made a surprising revelation: the service gets 1.8 billion logged-in viewers every month. And that doesn't include people who aren't logged in -- which means the actual number of people watching YouTube is definitely much higher. From a report: Last June, the service had 1.5 billion logged-in watchers. On TVs alone, people are now watching 150 million hours of YouTube every day. The latest figures are yet another sign that YouTube's reach is staggering, something that Wojcicki wanted to make crystal clear for the audience of advertisers and potential partners at its annual BrandCast event.