Have you already took a look at BS.Player Options window?
There you can set/unset BS.Player as the default player for the preferred filetypes (mms protocol included)
Just open BS.Player, press
CTRL+P to open the Preferences window (or open it from the player menu
Options -> Preferences).
Now choose
General -> File types section and uncheck all the extensions you don't want BS.Player to be set as default player. At the bottom you can also uncheck mms protocol association.
Let me know if this helps you
