It is said the best things in life are free, and the point is reinforced by a couple of really useful no-cost utility programs which bring AirPlay — Apple’s system for streaming video to an Apple TV — to your Mac. Normally, AirPlay only lets you play video from an iPad 2 or iPhone 4S.
AirFlick, by Erica Sadun, lets you drag and drop Apple-supported audio and video files (.mp3, .m4a, .m4v, .mp4, .mov) for playback on your Apple TV, if it is set up for AirPlay. Awesome. AirFlick only works out of the box on Snow Leopard (Mac OS X 10.6.x), but not any newer or older version of Mac OS X; keep reading to learn how to get around this problem.
AirFlick can also try to play other video formats (e.g. .xvid, .avi, etc) if you have VLC installed, but it doesn’t play them well, according to its own documention. Instead, Erica suggests you use Air Video Server, by InMethod, in conjunction with AirFlick.
To use Air Video Server, you choose “Preferences” from its icon in the menu bar; then, under Shared Folders, drag in any folders, or iTunes playlists, containing videos you wish to play. Once this is done you can close the window. Back in AirFlick, click the AirVideo Access button, and you should see the contents of the folder you chose listed in the drawer that slides out. Click on what you want to watch, and click the Play button in AirFlick. If the Apple TV reports a playback problem, press menu a couple of times on its remote.
If you aren’t on Snow Leopard, here’s what you need to do to make AirFlick operate without Air Video Server (though it’s still recommended that you use Air Video Server for non-supported video formats). Download both Mac OS X 10.6.8 Update Combo and Pacifist. Open the .dmg file for the Update, and then open the package therein from Pacifist. Search for mediastreamsegmenter, and then click on it (not “mediastreamsegmenter.1″). Click Extract and save it to your desktop, and quit Pacifist. Then, in the Finder, choose “Go To Folder…” from the Go menu, and type /usr/bin and click OK. Drag mediastreamsegmenter into the folder that opens, and enter your administrator password. AirFlick should now work as it does on Snow Leopard.