Well I think it is truly broken in 1.5, as in not a feature of the .exe any-more as far as I've heard, so unless anyone knows different or you want to reverse engineer your mod to run under 1.2 just to get a video of it, you need some other method of capturing the video.
I've seen Fraps and Game Cam mentioned but haven't got round to trying either. To explain that a bit more - I think you'd still set up the battle replay using -movie_cam to set the camera path, but capture it via a separate screen capture utility.
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