This is awesome! I work in the cash register software development world, and our customers are sometimes quite picky about the latency of our systems as a whole

This is awesome! I work in the cash register software development world, and our customers are sometimes quite picky about the latency of our systems as a whole (= the time between a scan of an item happening, indicated by the scanner beeping and lighting an LED, and the output being visible on the display). I found myself measuring this total latency using an iPhone (at that time it was a 4, without the high speed camera, but nevertheless sufficient to see whether we were below the critical limit of - at that time - 200ms), and it worked out very well, although I had to load all the videos into external software to count the frames accurately because the phones' own players weren't sufficient and there were no apps like this. I will definitely give this tool a try, it could vastly improve future measurements using the same technique :D