I've had a great experience with this add-on. I downloaded it in a rush when I heard a song I wished to identify on a radio site on my browser on pc. I half dowloaded it thinking it wouldn't work and was pleasantly surprised when it did. Librezam works by actually listening to the music played as the radio site I was using had no indication of what song was playing. The only thing to note is you have to be on the tab that the audio is coming from, it won't just listen to any song playing on the browser. 10/10

Edit: You can change the settings to have the Librezam listen to other tabs 11/10