problem with "Extend picture to" feature

[JoeR]

Hi.
before i'll ask the question i just want to mention that im using tv-out to watch movies on my tv, i have Geforce 6600GT in Clone mode and the "draw subtitles to overlay surface" option in bsp is turned on (so i could see the subtitles on my tv screen).

Now, what im trying to achieve is that no metter what is the original movie size, it will allways be stretched to a fixed size. So far so good, all i have to do is to set the Aspect ratio in the playlist to the size i want, right?- nope. Because i also want the subtitles to be on the black area, under the movie. So i tried to extend the movie size (video> video rendering> extend picture to) but then, it doesn't stretched to a fixed size.
Why does it happening?

thanks :)