Information/File Manager
Depending on the number of categories you require to handle, you could always use a combination of the finder with the built in label functionality, thus a movie can be held in one area (movies directory, for example), but "tagged" as something else.  Using smart directories and saved searches you can view your files by a combination of the attributes (location, label, media type) to create custom views.  All without purchasing software.  Cheap and cheerful, but may be suitable to your needs.