Re: Xorg, 2 devices and screens, xvideo perormance on Screen 1
I did not experienced that problem, but yes, Xv performance on tv-out (tried composite,svideo) are really bad for me too.
Overlay 'is said' to be unsupported by new hardware (even if i can enable it on windows side, very strange isn't?) , so the only choice for me was to enable the opengl video out driver (this means you'll consume more (cpu)power to play high resolution video).
I don't know about 6800, try xvinfo|grep Adaptor to see if you have overlay.
Or, to reduce a bit the cpu use with mplayer and opengl video output, do:
mplayer yourvideo.avi -vo=gl:yuv=6
...I still wonder why play a video on tv-out has became such a pain, with that good old 4400ti it was so smooth!