Comment 3 for bug 55646

Confirmed on a thinkpad X31, Kubuntu Gutsy:

01:00.0 VGA compatible controller: ATI Technologies Inc Radeon Mobility M6 LY

ii xorg 1:7.2-5ubuntu13 X.Org X Window System
 ii xserver-xorg 1:7.2-5ubuntu13 the X.Org X server
 ii xserver-xorg-core 2:1.3.0.0.dfsg-12ubuntu8 X.Org X server -- core server
 ii xserver-xorg-video-all 1:7.2-5ubuntu13 the X.Org X server -- output driver metapackage
 ii xserver-xorg-video-ati 1:6.7.195-1ubuntu2 X.Org X server -- ATI display driver

but for me the suggested workaround gives an error, I have to use instead:

$ xvattr -a XV_CRTC -v 1

With Edgy, the external monitor would always work, and movies would show on both screens.
With Gutsy, it only works if I start X after plugging it in.