Slow motion was an accident. It was an unintended side effect of another film invention—a projector meant to cut back on flickering, created by an Austrian priest-slash-physicist named August Musger in 1904. Which makes for a suitable statement about the replay review that slow motion has allowed for all these decades later: Replay does what it’s meant to do, but it’s created a set of side effects that are just as notable as the institution of video review itself.
For MLB—which became the last of the four major professional sports to include replay review in 2008, and introduced its current challenging system in 2014—these side effects have been varied.