Blade Runner
There's the whole "Tears in rain" scene, which to me symbolizes the ephemerality of life. So imagine what will be left of us in a 1000 years time or even a 1,000,000 years. To appreciate this movie is to lament the inevitable destruction and loss of all your memories, culture, and anything you hold dear. Every book, every song, every movie, every person.
Same thing applies to [Not a movie but a television episode], The Next Generation S5 episode "The Inner Light". I didn't understand it's true meaning when I was younger, 45 minutes of viewing Picard grow old, I thought. I called it "The Inner Shite". Then when I got older I started thinking about the future of humanity and what we leave behind. I'd argue that the message is even more poignant with Picard finding the Ressikan Flute after his experience, that flute represents the hope that something of our lives and culture will continue beyond our lifetime.
Lament with me brothers & sisters.