this is what wmp11 says in the help files under what can i share.
In addition, the file must be of one of the following types:
Music files, such as Windows Media Audio (.wma), MP3 (.mp3), and WAV (.wav) files. Note that audio CDs inserted into your computer can't be shared.
Video files, such as Windows Media Video (.wmv), AVI (.avi), MPEG-1 (.mpeg, .mpg), and MPEG-2 (.mpeg, .mpg) files. Note that DVD-Video discs inserted into your computer can't be shared.
Picture files, such as JPEG (.jpeg, .jpg) and PNG (.png) files.
Playlists, such as Windows Media playlist (.wpl) and MP3 playlist (.m3u) files.