Watching home video on Apple TV

think it has to be in iTunes on a computer running at the same time on the same network

or maybe if one pay for music match it can be in the cloud iCloud Music Library: Understanding differences between Apple Music and iTunes Match - Apple Support

To stream it from the net, you need to use either iMovie Theatre or share it using photo sharing.

Other wise you need to use you local computer as the server and use home sharing.