Comment 8 for bug 1063690

Same here with intel ivybridge. If unredirect fullscreen windows is enabled you *will* get video tearing unless the application is smart enough to pageflip on its own, due to a limitation with the intel hardware/drivers.

With modern intel hardware (sandybridge+;With 945gm both legacy vsync or page-flipping should work to eliminate tearing), its not possible to get tear-free output unless you are using a page-flipping compositor (like compiz). If you bypass compiz you rely on the application to properly pageflip. I tested this compiz build on ivybridge and got tearing:

In totem fullscreen
In firefox with flash 11.2 fullscreen
In VLC with openGL output enabled

I didn't get tearing:
In google chrome with pepper flash 11.5, with pepper flash opengl rendering enabled in about:flags. Enabling this by default for intel users will create tearing issues for a lot of people.