I have seen a ton of users (including myself) try to get TV-out working in linux to no avail. Well I have figured out how to setup TwinView to out put the screen from my CRT to the TV. I will post below the relevant X.org configuration. This works great in Fedora Core 3 and Ubuntu 5.10 onward (currently using Fedora 6 and Ubuntu 6.10).
The Meat
Basically there are two parts to modify. The first is the modules. Firstly, remove all references to DRI. Add the v4l module in. You should already have glx, but if not add that
Section "Module"
Load "glx"
Load "v4l"
EndSection
Next you will need to edit your video card settings. Make sure that your driver is "nvidia". Then add in ALL of the TV section there. Read up on what they all do, but the major ones that may cause a failure is the refresh settings,standard, format, and meta-modes. Fix them as needed. Mine of course is for the USA, using composite out, cloning the screen.
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "Gainward"
BoardName "NVIDIA GeForce FX 5700Ultra"
Option "NvAGP" "1"
Option "RenderAccel" "1"#TV Out Setup
Option "TwinView"
Option "SecondMonitorHorizSync" "30-50"
Option "SecondMonitorVertRefresh" "60"
Option "TVStandard" "NTSC-M"
Option "TVOutFormat" "COMPOSITE"
Option "TwinViewOrientation" "Clone"
Option "ConnectedMonitor" "CRT, TV"
Option "MetaModes" "1280x1024,1024x768; 1024x768,1024x768; 800x600,800x600; 640x480"
EndSection