Zend certified PHP/Magento developer

(FFMPEG ) How to stream video file (WITHOUT AUDIO) with audio coming from the desktop (from playing songs in the browser)

I have a mp4 file and I want to stream it with ffmpeg to youtube.
I am able to do it when using anullsrc so that I tell youtube those videos has no sound and it works okay.
But I do want audio, I just want the audio to be the audio captured from the browser where I am playing my playlist. I don’t want to download this playlist to mp3 and then provide the mp3 file.

Is it possible?