Confused about installing on another Mac

[Antivirus]

So I know that you can buy a copy of Mountain Lion and then install it with 5 other computers that you own.

Here is my situation, my brother and I both have Macbook Pro's. He is going to purchase Mountain Lion. Now from reading posts and searching around it seems that if he wanted to install Mountain Lion on my macbook as well he would have to Log onto my computer and then sign in on the Mac App Store under his name on my Macbook and then download like that.

Is this correct??

My confusion is that I have apps from the Mac App store under my own personal Apple ID as well as music purchased in Itunes under my own Apple ID.

If he downloads Mountain Lion onto my computer under his name does that mean everything under my Apple ID is lost or cannot be used in Mountain Lion??

 

[WhoisMedina]

You can create a bootable thumb drive with this then install it on the other computer.

 

[robbier]

Your brother can login to the Mac App Store on your computer using his Apple ID, download Mountain Lion, and then logout after the download has finished. You can then log back in. The downloaded installer will still be in your applications folder, ready for installation.