Google for the first time has disclosed that YouTube users daily watch over a billion hours, declaring it as a "big milestone" for their service.

"Let's put that in perspective, If you were to sit and watch a billion hours of You tube, it would take you over 100,000 years." YouTube vice president of engineering Cristos Goodrow said in an online post announcing the achievement.

Online video consumption has been soaring, with Google, Facebook, Twitter and other Internet firms working to increase audiences along with their cuts of advertising dollars typically devoted to television.