The blackout seemed to have affected devices across the board; both the PC and mobile version (Android and iOS) of the app displayed the same error message. In the case of mobile devices, we could still search for videos on the service. It’s when we tried to play them that the error messaged popped up. As mentioned, the blackout seemed only to have last for a couple of hours. The service is already back online, but Google has yet to issue any official statement as to what caused the downtime.

YouTube Was Down Across All Platforms  Users Greeted With Error Message - 66