I understand that my late 2009 iMac does not support Airplay mirroring according to Apple's requirements. I have Mavericks and the latest versions of iTunes installed. However, iTunes does allow me to mirror both audio AND video to my AppleTV 3. So why can't I mirror my desktop as well? I would think movies are more graphical intensive than just a desktop display. I already know about parrot, so this is not about getting 3rd party software. I'm just curious.