Originally posted on Cperky's Blog:
Home sharing is a feature that, simply put, links all your devices and computers together.
If you download a video on your computer, it will instantly start downloading on your iPad if you have this feature turned on.
To enable it, go to Video -> Home Sharing, and enter your Apple ID and password. This will link your iPad into your Home Sharing link-up (you can later turn this off if necessary).
Have fun with your iPad!