TV out will not work unless you have the ivtv_xdriver rpm installed which is on the MythDora disk in the MythDora directory. http://www.mythdora.com/?q=node/3548
To the end of all 'kernel /vmlinuz...' lines in /boot/grub/grub.conf, append 'vga=791', then reboot your system. This tells the kernel to load a frame buffer for your video card at 1024x768, 16-bit color. I use this all the time myself