The source of the mysterious 11 second Webdriver Torso videos on YouTube has been revealed to be...
Google, which uses the account to check quality of uploads. As reported on Engadget:
Clips are sent to YouTube's servers and then compared against the original file to ensure that the quality remains the same. The account going viral was just an accident, though once it happened Google was more than happy to play into the fun.
Here is Google's official statement on the matter.
We're never gonna give you uploading that's slow or loses video quality, and we're never gonna let you down by playing YouTube in poor video quality. That's why we're always running tests like Webdriver Torso.