One of the goodies inside OS X 10.8 Mountain Lion is AirPlay Mirroring. This feature allows for streaming wirelessly whatever is been displayed on your Mac to an Apple TV hooked to a TV.
Since updating, some have stated that the feature is not working. It turns out that your Mac has to be one of the most recent models.
- iMac (Mid 2011 or newer)
- Mac mini (Mid 2011 or newer)
- MacBook Air (Mid 2011 or newer)
- MacBook Pro (Early 2011 or newer)
AirPlay Mirroring requires Intel processors of 2nd and 3rd generation (Sandy and Ivy Bridge) for their video encoding capabilities.
Check the model of your Mac by clicking the Apple icon on the top left of the screen, then clicking "About this Mac" and then "More Info".