i remember seeing a movie on educational TV right around 1970 about a future dystopia where people who have lived to a certain age are isolated from the rest of the population. then, when they get to another age, they are( IIRC) put to death.  i  think the place they were isolated was near a beach.  this movie was filmed with what i call “soap opera” video quality, obviously on soundstage, if you know what i mean. i can’t remember anything of the story beyond what i said above, just that there was a lot of arguing.