How to convert flv files to mp3 offline?

I have got a few vids from youtube,etc but they're in flv form , (i dont want the procedure to get them in another way like ultraget) but flv video converter a free converter that would convert my already downloaded videos to mp3s
SUPER is nice free video converter, it can convert flv to mp3, it's totally free without any limitation and watermark, here is the download I'd prefer using this all-in-one video converter, my friends recommend it to me, it's easy to use flv player and works pretty well all the time, I think it deserves a try, and here is a step by step guide about how to free download and use it If you have any other questions, feel free to email me.