I've gotten okay results with a few clips, but it is not at all an intuitive process. In particular, I've never gotten a decent MPEG out of mediarecorder. This is a program from Berkeley that takes a set of still frames and encodes an MPEG from them. The interface is not at all convenient but it does create good clips. You'll need a parameter file, such as this one .
More documentation is available through Berkeley.
The basics, though, are that you generate a set of images, preferably PPMs, all in the same directory. I had a problem on IRIX, though, where the decompression processes were orphaned and filled up my per-user process count. If you are using Geomview, then life is pretty good. You can also do this by hand via the save menu, but for this gets old very quickly. My solution was to add a bit of code in the player portion of my GUI so that after displaying a new frame of the path I take a snapshot to a numbered file.