An MSWMM file is a movie created with Windows Movie Maker. It contains a project, which includes the movie timeline, transitions, and references to video clips, audio files, and still images used by the movie.

Windows Movie Maker allows the user to combine and edit content saved within an MSWMM file. Once the movie is finished, it can be exported in a standard video format or burned to a DVD. You can convert an MSWMM file to a .WMV file, which is a more common format, using Window MovieMaker: Windows Vista - Open the MSWMM file by selecting File → Open Project. Then select [m[File → Publish Movie[/m] and follow the prompts to save the file as a WMV file. Windows 7 - Open the MSWMM file by selecting File → Open Project. Then, drag the project to the timeline and click "Save to my computer", which is under "Finish Movie" in the left pane. Then follow the prompts in the wizard to save the file as a WMV file. You can also convert MSWMM files using Wondershare Video Converter. With this program, you can convert the project to more popular formats, such as .MP4, .AVI, .FLV, .MOV, .DVD, .VOB, an .MPG.