When you download MP4 files from paid download sites, such as iTunes, those MP4s are DRM-protected. DRM is a safeguard placed in files to protect against the illegal download and sharing of copyrighted music, but this protection also makes it difficult for people who have paid for and legally downloaded the music to utilize the files anywhere other than on their computer, including on portable media devices such as MP3 players and cell phones. If you want to make the files usable in these devices, you will have to get past the copy-protection. Writer Bio
