It's apparently all busted. Jordan Crouse has more details.
fixed in rawhide.
The Xv bugs are still there. This is a tracker bug to note that it's something that we need to make sure is fixed down the road.
Traditionally, the GX pitch must be a power of 2 based to allow us to compress the data to limit bandwidth usage when we send the video to the video processor. That worked out to a pitch of 8192 when the OLPC board was in 1200x900 mode - using up 7.6 of the 8MB of memory available. Thats why video wasn't working in Xv mode - the Xv driver couldn't allocate the offscreen memory it needed. Luckily, when compression is turned off, we are free from the power of 2 requirement. Commit 38f3d21beba13daba4844a129f3c268b5f291fb1 in the xf86-video-amd driver on freedesktop.org adjusts the pitch to a sane value when compression is turned off in the xorg.conf file. When we make the pitch linear, that saves us 3Mb - giving us plenty of room for Xv to do its thing. Apply the patch, and set option "NoCompression" "true" in the xorg.conf.
Jordan fixed this upstream in the amd driver.