Can't play video files on tv - black screen

[br0dy]

Hi, I'm new to this so please bear with me.

I'm trying to play video files on my tv, from my laptop. I have hooked it up with the s-video cable and I can view my desktop etc. on the tv, but when I play a video file (in VLC or Windows Media Players) it only shows as a black area on the TV screen, but it plays fine on my laptop screen.

Any help is appreciated.
Thanks

[happylily]

what is the video format?
and is it the one tv support?