How can i get the password for a user from Active Directory
Administrators do not have access to users passwords, only the ability to change them.
I doubt very much if this is possible considering it is a password. But you might have better luck asking this in ServerFault?
I'm not sure if you will be able to get access, but once its out of beta you'll be able to register.
Simple, you cannot. Passwords are not stored in nearly all authentication systems. Instead, they are converted into a 'hash' that is stored instead. Then, when you want to prove that you know the password, you convert the password you type into a hash using the same algorithm and compare that to the stored data.
Some use public/private keys to perform the hashing, some use alternative algorithms. None of them can "un-convert" the hash back into the original password.
You'll need administrative access to a domain controller to get the hashes. You'll then need to use a hash cracker, such as Cain, to see if you can recover the passwords. If the password is not simple, this could take days or years.
Note that this is illegal in most situations, and it's usual to reset passwords rather than recover them.