patent, at 2:47-53; '7,907 patent, at 2:61-3:4. The viewer control signal is not "implemented," and "generated and processed," until the processing system transfers video signals to either the first communication interface or the second communication interface. In Comcast's Remote Tune, no video is transferred to the first communication interface (i.e., Comcast's coaxial cable network) until after the set-top box sends a start session message to the VOD system. Thus, the set-top box is necessarily involved in generating and processing the viewer control signal.