YouTube announced on there Official YouTube Blog earlier today that Google have pushed a beta feature live that allows YouTube users to view 1080p video in a variety of 3D modes.
This 3D conversion process was originally added as a beta test during September 2011 when Google started encouraging video creators to try out the new feature. While Google recommended using a 3D camera for better results, the process works for all 2D video uploaded in high definition quality regardless of camera.
3D option - YouTube
In order to switch over to the 3D view, users must click the gear icon in the toolbar of the video. If the video has been converted over to 3D already, an icon will appear to the left of the gear icon and switch the video to the 3D view when clicked. The user can click the 3D icon a second time to bring up a variety of viewing options
