This is exactly what our extension does, if you were careful, you could see in the installation page that it is displayed there that it redirects you to another site where the conversion is done.

"This extension uses an external online service to convert and download YouTube videos to MP3. For this purpose the video URL is transmitted to mp3 convert (mp3convert.org) to start the conversion process."

Can you send us a print screen? We are not seeing this redirect.