One of the killer features of OS X Mountain Lion is AirPlay Mirroring. Just like on your iPad or iPhone, AirPlay Mirroring will allow you to beam video and sound from your Mountain Lion Mac to an Apple TV connected to your television set. The result? If you’re someone like me who watches a lot of video on his MacBook Air, you’ll never have to reach for that Thunderbolt-to-HDMI converter again.
There’s only one problem with AirPlay Mirroring in Mountain Lion: inexplicably, it doesn’t work on all Macs. In fact, unless you have an iMac, MacBook Air or MacMini from mid-2011, or a MacBook Pro from early 2011, you can’t get in on Mountain Lion’s streaming action.
Why? One theory is that it’s all about DRM.