There is no need to register plugins for BSplayer, the only thing to do is to place the plugin into the Plugins folder and then restart the player.
The plugin you mentioned is not made for BSplayer, and that's the reason why it's not included in the Plugins list.
Other BSplayer plugins you can try are the following:
Filename in OSD MSN plugin New Tag in Subtitles WinAMP Pause
and there are others...
If you want to create a plugin for BSplayer or whant to suggest someone to create one for you, take a look at the SDK folder in BSplayer installation directory.
Bye
