I just discovered this same problem. I have a DVD encoded with mp4 at 720, and it doesn't display on the TV-out, only plays sound. It does play on the N900 screen. Also, none of the camera-recorded videos play on the TV out either,as mentioned above. I do have a few (very) smaller-res Divx vids that do play on the TV, though.

Why should higher-resolution videos fail to play through TV out? What's the point of supporting high-res if it doesnt play on the TV?!?! And even the internal-codec camera videos,too? WTF?!?!

I can't remember if I had this problem before, I dont think I did but I could be wrong. It's been a while since I've messed with the TV out function.

Other TV-out funtions work ok, though. The destop shows up, and video games like MAME, Mupen, etc. show fine.

Suggestions?

Shinig, what do you mean by "don't go for the highest resolutiuon, try fine 4:3", anyway? Do you mean encoding resolutions? Or some internal, N900 video-out setting?