In order to use AirPlay Mirroring – the new screen streaming feature Apple built into Apple TV and Mountain Lion – you need a Mac bought in 2011 or later. So if you have a Mac from 2010 or before you’re busted, you won’t be able to mirror your Mac’s desktop to your Apple TV even if you have Mountain Lion installed. Apparently the reason is the lack of graphics power, says Cult of Mac. The on-GPU H.264 encoding (if you really need to know). Someone else told me it’s because of content licence problems. But don’t give up, this is where AirParrot comes in. For a reasonable $10 you can enable AirPlay Mirroring on your pre-2011 Mac. Simple as that!