Why can't I see any OSD on my TV-Out?

Both ATI and NVIDIA cards have a Theater or Cinema mode for the TV-Out display. In this mode, nothing but the video is displayed on the secondary display device. You shouldn't use these modes as they limit your interaction. Instead define the TV as a second display device (so you can see the desktop), make sure Overscan is enabled (this can be done in both the Radeon cards using one of the tweaking tools, or using the 4x.xx+ drivers on the NVIDIA, or through TV Tool). If you don't see any video when using this monitor setup, see this FAQ entry.