If we're waxing lyrical, there was a research paper out of Ireland from a small telecoms research outfit, circa 1996 describing pretty much this, but using tele

If we're waxing lyrical, there was a research paper out of Ireland from a small telecoms research outfit, circa 1996 describing pretty much this, but using teletext subtitles. In addition to capturing and indexing the subtitles, it also captured the video, and so allowed the captions to be used as an index to the video. I don't doubt someone can come up with an even earlier incarnation!