First off this doesn't happen all the time but does often. When i download a movie or a clip and try to preview it, it will say something about i need a license or it will say Unable to render video; DIVX decompressor not found. They say that either in my windows media player or real player. I don't get it. Any help is greatly appreciated. thanks

Many a forum member would recommend against trying to play a video that asks for a licence. What often happens is it will want you to connect to the net & send you to a spam/scam site or dialler recorder. See What you should know about WMA Files which also applies to wmv files.
Sounds to me you need xtra codecs such as either: A. http://www.land.ee/d_nimo_codec.html or B. http://www.free-codecs.com/

Good idea to get a backup player just in case such as VLC which plays all but the odd wmv file & is free: http://www.videolan.org/vlc/ (choose nearest mirror site)

Thanks for your help. I appreciate it.