Firefox>Preferences>Downloads at the bottom is the prefs for mime types. If the Real plugin installed, it will override your choices in this section.
Otherwise a single click on a .ra file will give a pop-up asking what you want to do with the file. Save to disk would be the choice. If the url is a .ram, then you have to save the .ram file and open it to find the true url. If it will only stream, the Wiretap it.
The plugin is in Firefox>control-click>Show PackageContents>Plugins not the Library>Internet Plugins
