I was having terrible tearing while playing any videos on my Ubuntu Oneiric 32-bit with Gnome 3 on my new Thinkpad T420 laptop with Intel SandyBridge Graphics Card.
I have googled around a bit, and found this only solution, haven’t investigated much behind it, but gave it a try, as I could easily revert it back.
I just added these two lines
to my “/etc/environment” file, then restarted, and surprisingly it worked out!! No more tearing whatsoever in any videos I play!
Update: This also solved the video tearing issue on Precise with Gnome 3.4
Source: post #32 on this page: https://bbs.archlinux.org/viewtopic.php?pid=1017705