his is a couple - and the man with the cam is a friend or another man for whom the couple does this performance. If you see the long version of this movie you can hear the last comment of the camera-man: "This was the sexiest work ever!"
wow, I love your description, I will soon experience all of this together with my wife who has been monogamous to me over 33 years and now has opened up to the idea of a real MFM-threesome in December!