Moreover, to infringe the '907 patents, the VOD system must implement a "viewer control signal" that is "generated and processed without the involvement of a set-top box for remote control." To perform the claimed method, the infringing system must "implement[] a viewer control selection indicated by the video control signal." '4,907 patent, at 7:12-14; see also '7,907 patent, at 7:64-66 ("transferring . . . video signals to a first communication system . . . if . . . indicated by the viewer control signal"). The role of the viewer control signal is described in the '907 patents as follows: