History of the National Football League on television
NBC was the first major television network to cover an NFL game, when on October 22, 1939, it broadcast a game between the Philadelphia Eagles and the Brooklyn Dodgers; the network was still only in its infancy, with only two affiliates, the modern day WRGB (now a CBS affiliate) in Schenectady and W2XBS in New York City. Portions of that game still survive via films, but the film is not footage from the telecast (recordings of television broadcasts did not begin until 1948). The use of a sideline camera, the sole camera used in the 1939 broadcast, would become the standard for all future NFL broadcasts until 2017; the angle is particularly suited for estimating yardage, compared to more mobile camera angles that began to appear in the 21st century.
Wiping
Similarly, all of the telecasts of the NFL Championship Games prior to the Super Bowl are believed to have been lost, with all surviving footage of those games coming from separately produced film. The status of most regular season and playoff games from the early years of television up to the immediate years following the 1970 AFL–NFL merger are also unknown. Among the footage that has survived include at least some of NBC's coverage from the 1972 AFC Divisional Playoff game between the Pittsburgh Steelers and Oakland Raiders that featured the Immaculate Reception, as well as the inaugural telecast of "Monday Night Football" from 1970 between the Cleveland Browns and the New York Jets, though several "Monday Night Football" games in the ensuing seasons were lost. A 1974 game that featured John Lennon being interviewed by Howard Cosell in the booth only survived due to a home video recording of the game; the game itself was wiped by ABC. CBS kept coverage of a 1978 matchup between the New York Giants and Philadelphia Eagles that would feature the now-infamous Miracle at the Meadowlands, although the existence of many 1978 games on CBS by private collectors shows that the networks by that point started keeping recordings of regular season games. There are rare exceptions of CBS games from 1977 back, but by 1978 the library of most teams is almost fully complete. NBC is another story.