This is how goal line cameras work - there's one at every race course and sporting event around the world. I had a weekend job running one at a race course grow

This is how goal line cameras work - there's one at every race course and sporting event around the world. I had a weekend job running one at a race course growing up. Nowadays they are digital I guess, but the technology is the same - you record only a sliver (the goal line) - the analog version has the film running past the sliver on spools, with the speed being adjustable based on how fast objects you want to record.