I noticed during early July while trying a rawhide LiveCD that the display was behaving very strangely like in the above video. During certain render operations, everything on the screen would "flip" horizontally in an annoying fashion.
* This happens during KMS boot while text flies by, before X has run.
* This happens while X is running.
* It happens continuously if you run gnome-terminal and have text fly by in your terminal. As long as the text is moving, the entire screen exhibits this glitch.
It is impossible to upgrade my laptop to rawhide while this bug exists.
kernel-2.6.31-0.112.rc4.git3.fc12 (both i686 and x86_64 effected)
krh mentioned that the "fifo watermark" work might be related to this.
*** This bug has been marked as a duplicate of bug 514106 ***