Windows Movie Maker 2 Winter Fun Pack is an application which runs only on Windows XP and below. As you can see on the official web page, the file formats supported by Windows Movie Maker in Windows XP are:
Video files: .asf, .avi, .wmv
Movie files: MPEG1, .mpeg, .mpg, .m1v, .mp2
Audio files: .wav, .snd, .au, .aif, .aifc, .aiff
Windows Media files: .asf, .wm, .wma, .wmv
Still images: .bmp, .jpg, .jpeg, .jpe, .jfif, .gif
MP3 format audio: .mp3