ASX is a Microsoft ASF Redirector File format. It does not contain any actual information besides the location of an ASF movie files. ASX files are handy and can be used in URLs to find the location of the actual movie file. An MP4 is a video file that contains MPEG-4 compression, which utilizes separate compression for the audio and video portions of the file. MP4 files are used for file sharing on the Internet. With a Mac you can find and convert ASX files to MP4 with QuickTime Pro and the Flip4Mac plug-in that allows QuickTime to play ASX and ASF files. Writer Bio
