like do you use some kind of special converter to convert the song to mp3 to FLAC?

There are various methods. You could use a jack that has 2 plug heads, so it runs from the TV's headphone jack to your computer's headphone jack, and simply record the music as it plays into audacity. You could also find a rom and rip the files (whatever filetypes they may be) and then use a converter. Still another way as with PS and N64 games is "hacking" the rom and forcing the audio data into a particular data type that you do know how to play (hence, PSF's, USF's, GSF's, etc.). These are pretty crude summaries but they're sort of the basic idea.

Thanks for the info.
I use almost 100 video converters i have and they are legit to :P