There are various ways to invoke CLAutoThumbnailer.
To process a particular video file:
CLAutoThumbnailer [options] videofilenameTo process an entire directory (and its sub-directories):
CLAutoThumbnailer [options] -d directoryTo process a multi-part video file (like a title set from an unencrypted DVD or a file that has been split into CDROM size pieces):
CLAutoThumbnailer [options] videofilename*To process a text file that contains a list of video files to process:
CLAutoThumbnailer [options] commandfilename.txt
Of course, you can also just say clatn if you followed the installation instructions.