" recognize the great potential of the cable technology to further the achievement of long-established regulatory goals in the field of television broadcasting by increasing the number of outlets for community self-expression and augmenting the public's choice of programs and types of services. . . . They also reflect our view that a multi-purpose CATV operation combining carriage of broadcast signals with program origination and common carrier services, might best exploit cable channel capacity to the advantage of the public and promote the basic purpose for which this Commission was created:"