One list of movie extensions, in effectcraft-project, with AVI added:
FilmCraft reads AVI 1.0 / OpenDML. Tests against ffmpeg fixtures: Motion
JPEG with PCM audio, an unsupported codec (imports and says why it has no
picture), a file that isn't an AVI (an import error), and a damaged one
(a truncated recording imports as far as it goes; a garbled packet loses
its own frame only).