I've never watched Julia Child on PBS, nor do I know how that program accounts for its ratings and marketing, which I believe has to do with public funding moreso than advertiser revenue, so I cannot speak to that example. However I will restate my thesis and attempt to be more clear:
(1) The NFL makes billions of dollars from ABC/ESPN, NBC, CBS and Fox
(2) The reason why those networks/stations pay so much money for broadcast rights is because so many people watch the games
(3) When people in here state "the NFL gains nothing from me because I don't buy NFL merchandise or buy tickets, I only watch the games" that is a fallacy. Even if all you do is watch the games, the NFL still makes money - and an awful lot of it - because of you
(4) An individual not being a Neilsen member is irrelevant to point (3). There are other statistical methodologies in play to account for the true number of viewers. Neilsen numbers are certainly important, but not all encompassing.
(5) And, since I apparently have to mention this for certain people in here (not you), no one single individual person registers as even a blip on the league's radar. You could spend your entire life ignoring (and I mean truly ignoring) the NFL or you could spend your entire life giving the NFL all your leisure time and money and they would not notice because you are only one single individual person. But collectively, as a group, all those people who "only watch the games" are still fattening the league's coffers.