Let's say I'm hosting a Hangout and want to share a QuickTIme movie file with the group. I select the screen share and call up the QuickTime video from my hard drive that I want to share.  It loads fine into the Hangouts window. It plays fine.  But the audio cannot be heard by anyone but me. They hear my voice fine, just none of the audio from the QT movie.  How do you mix audio?