Instructions
Turn on both the PC and Xbox 360. Make sure there is no disc in the Xbox 360's tray so that the console boots to the dashboard menu.
Insert the ethernet cable into the Xbox 360's ethernet port located next to the audio/video ports. Plug the other end of the ethernet cable into your computer's ethernet plug-in. See the computer's manual for the location of its ethernet port if necessary.
Run Windows Media Player on your computer.
Click the "Stream" button in the upper-left corner of Windows Media Player.
Click the "Turn on media streaming" option from the "Stream" menu. A dialog box opens.
Click the "Turn on media streaming" option in the dialog box then click "OK" to finish enabling media streaming.
Scroll up to find the "My Xbox" section on your Xbox 360's dashboard.
Scroll right to find "My Videos." Press "A" to open it.
Select "Computer" when prompted for a media source. Your computer's video files appear.
Select a video file for playback on your Xbox 360.