You werent the only person to waste a lot of time on YouTube this year. In March, the video giant reached 1 billion monthly unique visitors. Altogether, over 6 billion hours of video — a 50 percent increase over 2012 — were watched each month. But what exactly entertained us during all those late nights in front of the computer? To cap off the year, YouTube released a tribute video (above) to its viral stars — including Mystery Guitar Man, Overly Attached Girlfriend, Annoying Orange, and a herd of stampeding goats — and ran down the years most popular videos.