If you’re still working on a project, you can save the project file and open it later to continue working with your movie. A saved project file in Movie Maker has an .mswmm file name extension. Before you save your project, you can include general information about the movie, such as the title, author, copyright, a rating, and a description, that is often displayed during playback by many media players.
Save a Movie Project
Click the File menu, and then click Save Project.
Select the folder where you want to save the project file.