This particular SIT file has a format I don't recognize. It's apparently valid, since StuffIt Expander can extract it, but the library that BetterZip uses doesn't recognize it and neither do I.

I don't understand developers who publish their software StuffIt compressed in a time when Mac OS X can handle zip files without extra software. If you are in contact with the developers of TimeSurfer, you could ask them to repackage their app in zip format.

And thanks for your kind words. That's always the best motivation.