What he is doing with his VNC controlled PC is picking content that the PC will play. What you are doing with your AirPlay device is playing it there and stream

What he is doing with his VNC controlled PC is picking content that the PC will play. What you are doing with your AirPlay device is playing it there and streaming it to your appletv. The device is doing the playing though; you are sucking its battery down. This is not what I would call the ideal experience. The ideal experience would be to use your device to tell the appletv where the content is and the appletv then does the playing/streaming. This would be easy for web content with a URI but unfortunately that's the extreme minority of all internet video content.