When you do this then you will find your movies in the "my movie" folder!
You need to download Connect360, this program will find the 360 wich is on the same network!
In the settings of the Connect360 is a fuction so you can choose wich folder to stream! (All files from itunes will be streamed anyway)
I made my HDD the folder of streaming! I therefor have 1100 movies on my Xbox (all backups offcourse

Hope this little guide will help some of you:D