From what I know about FilmGimp it is a frame editor compatible with doing film and video work.
Think Photoshop for video instead of stills. I don't think FilmGimp is capable of doing NLE.
From
http://filmgimp.sourceforge.net/
Film Gimp is a free open source painting and image retouching program designed to be more suitable for film work than GIMP or Adobe Photoshop. Film Gimp is the most popular open source tool in the motion picture industry -- used in Scooby-Doo, Harry Potter, Stuart Little and other feature films. The remarkable color range of Film Gimp appeals to 35mm cinematographers and photographers because film scanners are capable of more color bit-depth than can be displayed on a monitor. Film Gimp supports many file formats, both conventional formats such as JPEG, PNG, TIFF, and TGA images -- and more exotic cinema formats such as Cineon and OpenEXR. It is a general purpose tool useful for motion pictures, print, and the Web.
Film Gimp is based on GIMP, the GNU Image Manipulation Program. Film Gimp is an independent project, separate from GIMP and GNU. GIMP is a widely-used alternative to Adobe Photoshop, a popular tool for professional image editing. Film Gimp extended GIMP to operate upon a series of images (with a frame manager) and in 16-bit linear or floating point color depths. Film Gimp, at 48-bit rgb, has much more color depth capacity than Gimp at 24-bit rgb. Although Film Gimp has more colors than can be displayed at once on a conventional 24-bit rgb monitor, it makes a difference when working with the higher dynamic range of film.
BTW, they are projecting to have an Aqua version in June '03. . . .