På http://plugindoc.mozdev.org/linux.html#RealPlayer hittar man anvisningarna:
Version: RealPlayer 10.0, Helix Player MS1 or later
SeaMonkey 1.0: Supported
Firefox 2.0: Supported
1. Install RealPlayer 10.
2. Copy nphelix.so to your Mozilla plugins directory and nphelix.xpt to your Mozilla components directory.
3. Make sure a symbolic link to the realplay script is in your PATH.
Punkt 1: Redan här stupar jag.

"....No application suitable for automatic installation is available for handling this kind of file"
Nåt fattas, men vad.