Instructions
Download and install a media streaming application on your computer. Applications that can stream files from your computer to your Xbox include Connect360, Rivet, PlayOn and TVersity.
Launch the application. Open the "Options/Preferences." Add your iTunes Media folder to the list of folders to stream. The applications will stream the detected media formats in the selected folders, including your iTunes music and movies. If you want to stream only your iTunes movies, select the "Movies" folder within the "iTunes Media" folder, which is located in your "Documents\Music" folder.
Power on your Xbox. Select "Video Library" from the dashboard.
Select your computer from the list of sources. The selected folders will display. Navigate to the "Movies" folder, locate the desired flick and select it to begin playback.