I had some headache and disappointments with airplay mirroring after installing ML and thought my methods to becoming thrilled with it might help others. First of all, the recommended airplay setting under the display preferences works quite well for a viewable desktop and decent video size. I found however that setting it to 720 made video playback fill the entire screen. However once I found a suitable size to play videos, they stuttered constantly. Like to the point that I figured this whole thing was just a nice proof of concept and would never be able to provide an enjoyable entertainment experience for us. The glowing reviews by the press and mixed (mostly positive)reviews in the forums pushed me to work on the solution. As simple as it sounds, the fix all for me was ethernet. Connect your Apple tv to ethernet and I bet your problems resolve. What really started to impress me though was what I found possible by remote apps in the App Store. The one that impressed me enough to pay was Hippo Remote. One touch access to YouTube lay back and Vlc and hundreds of other things is amazing. I hooked up a huge hard drive to my router and now I finally have an easy and elegant way to watch movies without having to encode or turn on my loud power hungry ps3, I guess none of these things is especially revolutionary. after all, I was able to do all of this before via a combination of ps3 and apple tv and an hdmi cable for the macbook. But now it's an easy all in one wireless media solution that I am totally digging. Oh and another tip – I don't know if it helps with cutting back on cpu use, but definitely check out nosleep if you're using a macbook. It is nice to be able to shut the screen while airplaying.