It's a good thing if you already have a video residing on your PC's hard drive. All you need to do to add it to your WMM presentation is to use the "Import video" utility and, in a snap, your video would be imported to your current WMM Project Collection. WMM supports the following video file formats, so all you need to do to successfully upload videos to your project is to check whether your video is in .asf, .avi, .wmv, .MPEG1, mpeg, .mpg, .m1v or.mp2 form. If your have any of those file extensions, then you can add it to your WMM project.
After importing the video file into your Project Collection, you may drag and drop it off the Project Timeline, similar to the way you do it for image files. To trim the video, you simply shrink it by pulling the video container to the left side, or pulling the video container towards the left to trim from the beginning of the video file.