Although the history of instant replay is a bit fuzzy, its use as a major viewer enhancement to NFL broadcasts pretty much began as the Super Bowl era was dawning. The innovation was a perfect fit for football given the time between plays to run replays. It also created a new dimension of analysis that could slow the game down and help fans better understand the nuances involved. At the same time, of course, it made every viewer into a referee without a whistle, and it was inevitable that the NFL needed to use instant replay to review questionable on-field calls and overturn those when necessary.
The league first adopted limited use of instant replay as an officiating aid in 1986, and now the technology is an integral part of the game – to the point that coaches are allowed to call for replay reviews of officiating decisions by using a limited number of challenges each game.
The NFL has been a sports leader in this area, partly because it is such a TV-oriented league. With teams playing just once a week, TV crews have historically been able to put more effort into the production of broadcasts, with more cameras capable to producing the angles needed to review the action.