I've had succes using one configuration using two monitors for "standard" x and another for one monitor and tv-out. Try using the attached XF86Config and then play a movie by using a script like:
XFree86 :1 vt8 -screen screen_tvout800 +bs -ac &
xset -display 0:1 s off
mplayer -fs -ao oss "$1"
killall -15 XFree86