A video-on-demand system transfers a control screen signal to a second communication system and receives a viewer control signal from the second communication system. The video-on-demand system transfers video signals to either a first communication system or the second communication system based on...http://www.google.com.tw/patents/US6757907?utm_source=gb-gplus-share專利 US6757907 - Display selection in a video-on-demand system
