[CentOS] FireFox and Plugins

While doing a browser fingerprinting survey, I was quite surprised to 
see I actually have a FireFox plugin installed.

The culprit is

/usr/lib64/mozilla/plugins/librhythmbox-itms-detection-plugin.so

It appears that whoever maintains the rhythmbox RPM has chosen not to 
package the browser plugin separately like it probably should be. So if 
I have the rhythmbox RPM installed, I have the plugin.

This is rather worrisome because I can find no trace of the plugin in 
the Mozilla preferences panel, so if it is there it is very well hidden 
and if it really isn't there, it can't be disabled there.

Is there some kind of blacklist file I can put in 
/usr/lib64/mozilla/plugins/ or ~/.mozilla/plugins/ to specifically tell 
FireFox not to load that plugin, or do I have to uninstall rhythmbox?

Thank you for suggestions.

PS does anyone actually have a real world use for an itms detection plugin?