Bob, Many of us use TVersity to assist the Mediashare feature to play a variety of formats. If you're interested, here are the specifics. Note that the current version does not work, thus the older version.
You might want to try a 3rd party software called TVersity. It takes the place of Windows Media Player as the server. The current version doesn’t work properly so I run version 1_7_4_1 and simply click “okay” if offered the update. In addition I run the CCCP codec pack (not Insurgent) and refuse the TVersity codec version if offered. One nice thing about TVersity is the Library tab where you can tell the program where to look for your files. Another advantage is that the program will trans-code on the fly several file types to ones the Media Share program can play. Note that you choose the “folder” option when selecting files to play.
http://www.fileol.com/audio-and-video/tversity-media-server-pro-1.7.4.1.html