Since a few months, after a fglrx-driver update, every video I tried to play appeared streched on the TV screen (the upper half of the image sctreched over the whole screen). If you experience a similiar problem just put this in the driver section of your xorg.conf:
Option "TexturedVideo" "on" Option "TexturedVideoSync" "off"
You may also need these lines:
Option "VideoOverlay" "on" Option "OpenGLOverlay" "off" Option "OverlayOnCRTC2"
Hope I helped someone as I searched for a long time until finding this.
Dammit, haven't been here in a while. Still rocking Arch.