https://www.sri.com/press/story/the-first-down-marker-how-te...
I interned for them one summer in... 1996?
They had sold their tech to Padres and Giants broadcasts initially to put ads on the outfield.
The first down line came a bit later and was a much better use of their tech.
Princeton Video Imaging even got a shout out (1-line) at the end of every NFL game for a while.
https://www.sri.com/press/story/the-first-down-marker-how-te...