Location of OS X Mountain Lion download file
After purchasing Mountain Lion OS (10.8) from the App Store for $20, the installer begins to download. If you’ve ever wondered or needed to know where the file download is, I’ve been able to locate it during the download (maybe uniquely named). I used a program called EasyFind with the parameters: Search For: *.*, Only Files, Operator: UNIX-Wildcards, Include: Package Content & Invisible Files & Folders. I sorted by SIZE and watched for the largest file to appear at the top of the search window and kept refreshing the list. The main file is called mzm.whodaifs.pkg.
Once finished though, immediately the folder above with the four downloaded files are removed and the installer is placed in your hard drive in the /Applications folder called Install OS X Mountain Lion. Once you launch this installer and finish with the installation, the installer is deleted. If you want to keep the file and create a USB installer for future use, select on the App, right click and select show package contents. Navigate into the Contents -> SharedSupport and copy the InstallESD.dmg file to your desktop or other location.