Thanks to the article(Installing AIR Runtime Environment on Mac OS X) at last I have installed AIR Runtime Beta 3 for Mac OS X Leopard.
The problem was in “air_b3_mac_121207.dmg.bz2″ file which I get from Adobe’s site. The file has incorrect extension *.bz2, it is automatically added by Safari but it’s useless. The file with this extension raise an error in Disk Utility: “There are not mountable filesystem in package”. So, after file was renamed to “air_b3_mac_121207.dmg” the installation of AIR Runtime executes perfectly.
