The audio is not extracted from the video shown, the audio is from the recording of the last mating call heard from the now extinct species of bird, believed to be sung from the last bird of the species.
The video was extracted from a data archive.
Apprently wikipedia was wrong. (shocking)
"In the 1970s, the only known footage of the bird was filmed by John L. Sincock on Super 8 film"
Other footage exists.
