The argument applies to any phenomena that can be unambiguously recorded. Given the ease of recording relatively high quality video / audio / IR, assertions of a recordable phenomena without unambiguous recordings implies the assertions are false.
There are plenty of recorded sightings of UFOs on youtube. Probably more videos than existed 50 years ago.
There are plenty of recorded sightings of UFOs on youtube. Probably more videos than existed 50 years ago.