codecs
 

some times I get message= unable to play, might need one or more codecs. Where do I get codecs needed for ALL videos?

http://www.divx-digest.com/software/nimo_pack.html
This is probably the codec pack.

Alternatively, you can try playing them in another player (if you're afraid that Micro$oft might be spying on you via WMP). Say, VLC or mplayer. They're both free ad quite good. Plus, they don't need any additional codecs. Just install and play.

www.videolan.org

http://www.mplayerhq.hu/homepage/design7/news.html