RealJukebox was computer software released by RealNetworks in May 1999. It allowed users to organize their digital music and rip music. First version of RealJukebox was released in May 1999 but By late 2001 all the functionality of the program had been integrated into the Real’s core media player program, RealPlayer.
RealJukebox is not available for download. Many plugins in RealPlayer are named with RealJukebox so users get confused with the software they installed. RealPlayer installs many plugins in browsers to add functionality, plugins includes RealJukeBox NS Plugin, Realone Player Version Plugin, Realarcade Npapi Plugin, Realplayer Download Plugin etc.
If you see RealJukeBox NS Plugin in Firefox plugins, then you must have installed RealPlayer in your computer. There is no direct way to update this plugin. You will have to update your RealPlayer to update browser plugin.
RealPlayer plugins enhance the users browser experience. Normally, they do not cause any problem in browser.