SolveigMM AVI Trimmer is a free AVI video editor, cutter and trimmer software that allows you to cut AVI movies extremely fast and lossless. It does not perform any encoding/decoding process thereby ruling out the possibility of any “out of sync” errors
You can edit AVI files to keep just the relevant part of it, remove commercials from movies, etc with this freeware application.

Features include:

Supports any video content (DV, XviD, DivX, 3ivX, etc.)
Supports any audio content (MPEG-1, MPEG-2 layer 2,3, AC3, etc.)
Allows trimming AVI files contained VBR audio without synchronization loss
Supports AVI files of the size more then 2GB
Supports the OpenDML AVI file format extension
Supports the native DV AVI format (both Type 1 and Type 2 in Microsoft terms)
Performs the trimming process starting with K frame accuracy (group of pictures)
Cutting off several portions of a movie at one time is allowed

Download here