"Remember in March when we shared with you that more than 24 hours of video being uploaded to YouTube every minute? Well, you continue to amaze us: you’ve increased the amount of video uploaded to YouTube to 35 hours per minute. That breaks out to 2,100 hours uploaded every 60 minutes, or 50,400 hours uploaded to YouTube every day. If we were to measure that in movie terms (assuming the average Hollywood film is around 120 minutes long), 35 hours a minute is the equivalent of over 176,000 full-length Hollywood releases every week. Another way to think about it is: if three of the major US networks were broadcasting 24 hours a day, 7 days a week, 365 days a year for the last 60 years, they still wouldn’t have broadcast as much content as is uploaded to YouTube every 30 days."
Source: YouTube blog, 10th November 2010