outputting video from iPhone 3G?

[(vikm)]

I'm watching a hockey game on my iPhone 3G using an app from the app store and want to know if it's possible to output the video and audio to a tv using the Apple AV cables. I've hooked it up to the tv and I can get the audio but the vid is a no go. Am I missing a settings change or something? Or is it not set up to allow for video output like this? Orrrr, is it dependent on the app being used?

Any input is appreciated. Thnx