Stitch movie part-files

A couple of days ago I downloaded a movie from Rapidshare which showed up in 8 parts with each one named something like filmname.avi.001 and so on up to filmname.avi.008.
I'd never come across this before as normally Rapidshare movies download as .rar files which can easily be stitched together on my Mac with Unrarx.
Anyway after just a little googling, I came across Catenator which did the job very nicely.
I should mention that I got a lot of help from this thread where several other stitching apps are presented.
The app downloads as a zipfile. After unzipping, I just moved Catenator to my desktop. Then I highlighted all 8 parts of the movie (i.e. each of the filmname.avi.00x files) simultaneously and moved them all together to the Catenator icon on the desktop.
When I tried to drag them to the icon individually the stitching took place on only a few of the totally meant to be stitched.
A small circle divided into quarters colored black and white appeared. This persisted for about 2-3 minutes after which a new file showed up on the desktop named filmname.avi.00
Now I just had to rename this to filmname.avi and the movie was ready for viewing.