Yes.
Make sure he's on your network, has iTunes open on his MacBook, and his iTunes is set to share his library.
On your AppleTV, go to the menu where you can change your library. There should be an option to select another library. You should see his library listed. Select it.
That will pop up an auth code on your TV.
If your friend opens iTunes, he should see your AppleTV listed under Devices. If he enters in the auth code from your TV, your AppleTV should be able to stream content from his MacBook.