Can you edit swf file on Windows movie maker? No. When you try to import swf file into Windows Movie Maker, you will find that if you drag and drop the swf file into Windows Movie Maker, there is nothing happen. If you click "Import video" and locate to your swf file, you also can find that your swf file is not show up.
Why? When you import video you can see Windows Movie Maker supported format incluing .avi, .mpg, .m1v, .mp2, .mp2v, .mpeg, .mpe, .mpv2, .wm, .wmv, .asf. So if you want to import a video format that Windows Movie Maker is not supported, then it can not recognized.
What should you do if you want to edit swf file with windows movie maker? As we know most of video editor is not support swf file, the easiest way to edit swf file is to convert swf file to other format, to edit with Windows Movie Maker, convert swf to mov is really a good choice, forWMV file is a Windows Media Video file.
To learn the detail of how to convert swf to wmv:
Source from: http://videotoolsformac.blogspot.com/2013/08/how-to-make-swf-file-editable-in.html