I guess it's a 70s movie about aliens who have come to earth and sort of "play" games with us just as we play and manipulate animals. The comparison is quite explicit in the movie. The humans who come into contact with the aliens totally forget about it later, but, at the end a man and a woman meet by chance. She's whistling a tune and he seems to "remember" it and asks her about it. They were together before when they were with the aliens but do not remember about it.
I think the aliens are actors wearing tight shiny leotard-like costumes. Quite cheap production indeed.

Laboratory (1980) (http://www.imdb.com/title/tt0229523/reference)