Editing AVI files is easily done through VirtualDub but for .wmv and .mpg files the Werkzeuge are less easily available. Two very good command line Werkzeuge are available for editing these files viz.

AsfBin - Very well done editor for Windows media files
MpgTx - A tool being developed largely for POSIX apps.

Both these applications are freely available for download for non-commercial use.

Movica is a graphical user interface that uses these fine programs to edit movie files. A great deal of emphasis has been placed on keyboard shortcuts to make the job of editing easier.

Briefly what you can do is -

- Select or delete multiple portions from a video file.
- Copy, paste and fine tune the selections.
- Join multiple files together
- Split movies into smaller ones
- Keep editlists that let you play selected parts of the movie without editing