That's actually pretty interesting but I see so many ways this is going to be used wrong like flash used to be. I'm nevertheless wondering about a song player in SVG and HTML5, have you ever seen one of those ?

http://dahlström.net/svg/audio/html5-audio-in-svg.svg

link?

Nice trick, but not that necessary. I learned that when I started to dig SVG files after this: http://www.coreldraw.com/en/pages/svg-file/ but I still can't figure out a valid use of having audio in SVG

But why should you?

Using audio/video tags in an SVG is outlined in the spec: http://www.w3.org/TR/SVGTiny12/multimedia.html#Smil2Media

You can link to audio in an SVG file.