If you want to download Yahoo Messenger 10 Beta offline Installer just visit here, or you can just download from the link that I give you below. The Version of this YM 10 Beta is 10.0.0.525-us and you got to know that there are few update features along with this 10 beta.
Download Yahoo Messenger Beta 10 Offline Installer Stand Alone
You can download the installer file of YM 10 beta just copy paste the links to your web browser below. enjoy.