Installing Audacity ( http://audacity.sourceforge.net/download/windows ) you can Import a Video and Export it's Audio, in many Formats depending on which Codecs are installed. Also Import Audio, and export in another format, plus record, multitrack, edit.
Have fun,
I could never figure out how a company could have the Audacity to make such a great program totally free.
I prefer it over many paid programs. 
Shhhhhhhhhhhhhhhhhhh Bob,
those of us who know how to use Audacity try to keep it under our hat so to speak.
However it is of course no secret, and I have to say I've spent many hours Recording and editing Soundtracks, and loving the fact I'm offered such a great programme, for free.
I think if we all give back in some small way, like donations, volunteer work, most developers of Freeware, and OpenSource Software are more than happy.
For instance Avast Home Ed.
