[quote]Do I need to add fps=29.97 at the end of my DirectShowSource command? I strongly suggest that.. it may work without but it's safer to specify it. And you also need to add -fps 29.97 before the -new in your mp4box commandline.. else you end up with 25fps video as you may have noticed.
As for playback, there are plenty of good tips in this and the container forum. Basically get the latest ffdshow and haali spliter (or ffdshow + install Nero).
As far as running mp4box goes.. you have the source
And if you're trying the alpha.. it might just be one of the million things that I broke since the latest stable release. I have the new version started for the first time now.. it's going to be a long while until everything works as it's supposed to.