A method performed using a computer associated with a television display and connected to a computer network and to a television signal source device, wherein: a television signal feed having encoded thereon primary television content is received from the television signal source device and the primary television content is presented via the television display; the computer is programmed to utilize data received via the computer network, including (i) first data comprising electronic indicia of a to-be-replaced portion of the primary television content and (ii) second data comprising electronic indicia of secondary television content; the computer is programmed to present automatically via the television display, using the second data, at least a portion of the secondary television content in place of the to-be-replaced television content; and the method being characterized in that: (a) during presentation of the secondary television content, automatically monitoring, with the computer, the television signal feed and comparing it with the first data; and (b) in response to detecting any difference, between the television signal feed and the first data, indicative of a user-control action with respect to the television signal source device, and without receiving the user-control action at the computer associated with the television display, automatically altering, with the computer, the presentation of the secondary television content in accordance with the user-control action. a television signal feed having encoded thereon primary television content is received from the television signal source device and the primary television content is presented via the television display; the computer is programmed to utilize data received via the computer network, including (i) first data comprising electronic indicia of a to-be-replaced portion of the primary television content and (ii) second data comprising electronic indicia of secondary television content; the computer is programmed to present automatically via the television display, using the second data, at least a portion of the secondary television content in place of the to-be-replaced television content; and the method being characterized in that: (a) during presentation of the secondary television content, automatically monitoring, with the computer, the television signal feed and comparing it with the first data; and (b) in response to detecting any difference, between the television signal feed and the first data, indicative of a user-control action with respect to the television signal source device, and without receiving the user-control action at the computer associated with the television display, automatically altering, with the computer, the presentation of the secondary television content in accordance with the user-control action. (a) during presentation of the secondary television content, automatically monitoring, with the computer, the television signal feed and comparing it with the first data; and (b) in response to detecting any difference, between the television signal feed and the first data, indicative of a user-control action with respect to the television signal source device, and without receiving the user-control action at the computer associated with the television display, automatically altering, with the computer, the presentation of the secondary television content in accordance with the user-control action.