Clip Library Management
I'm not sure that it would be ideal, but Lightroom is able to provide keyword and cataloging support for a variety of video clip types.  It isn't expressly designed for it, but it's a relatively cheap option that may be able to handle your needs.

As stib was nice enough to point out, Adobe Bridge also can do similar cataloging if you have the broader Adobe suite or you can try using Darktable which is an open source package similar to Lightroom, though I have no direct experience with Darktable's ability to catalog video.