[Tips]how to find MAS downloading file url

some times Mac app store application download Mac OS X update package very slow, so I write this tips.
First use MAS app start downloading
second open terminal:

rMBP:~ yarshure$ lsof |grep apple.com
WebProces  304 yarshure   33u     REG                1,3     12288   756415 /Users/yarshure/Library/Safari/LocalStorage/http_support.apple.com_0.localstorage
App\x20St 5400 yarshure   11w     REG                1,3 117339677 11229520 /private/var/folders/bk/j1vyw0wd1nx8lldrzc4z8z300000gn/C/com.apple.SoftwareUpdate/swcdn.apple.com/content/downloads/53/57/041-9585/m24b4n13ngu3s79fguytcmmzsojk1sb2o2/OSXUpd10.8.3Seed.pkg

apple update package downloading server is swcdn.apple.com, so we found the url is:

http://swcdn.apple.com/content/downloads/53/57/041-9585/m24b4n13ngu3s79fguytcmmzsojk1sb2o2/OSXUpd10.8.3Seed.pkg.

aha,very easy! I have used this method  several times  download Mac OS X 10.8.3 Beta update package.