iTunes DRM files include AAC, M4V and M4P. If you don't remove iTunes DRM it's impossible to play them on any Apple incompatible devices like Zune, Creative Zen, PSP, mobile Phone, etc. This turns out really bad if you want to buy a new mp3 player which is not manufactured by Apple.
You could try some methods or programs that remove DRM off of the iTunes files. Please note that using programs might be illegal in the country where you are living, make sure you know what you are doing before downloading and using them.
Download M4V Converter Plus and make a free try. You could convert M4V format video to any unprotected video formats. Such as MOV, MP4, or customize for iPod, iPhone. With this M4V converter, you can convert iTunes store video to any format simply.
Click Add Movies, and then choose the M4V video files you want to convert. Click Add.
To convert m4v to mp4, you can simple to click Convert to drop-down list to select Same as source for mp4.
