MP4 is a container so what's inside may not be supported. Try transcoding it to something tame with HANDBRAKE. There are so many tutorials on what a MP4 container is, and transcoding that I'll pause here.
Bob
I have used DVD Flick for sometime, but at the moment I have a couple of files it won't accept, with an error message 'no usable video track'
They are normal MP4 files as far as I know, and play OK on my laptop. I have also tried them converted to AVI (with Video Toolbox), using a couple of different video codecs for the output (Divx, MPEG4), with the same result.
Has anyone any idea what is the problem? (In terms the non-expert might understand if possible)

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