A few years ago (maybe it was in 2001. I don't remember), 2001: A Space Odyssey had a brief nationwide theatrical run. This was my first opportunity to see a movie that was made to be shown in a theater before I was born on a big screen, as it was intended. I had, of course, seen the film before, but always on Television, which until only recently meant NTSC video. Seeing it in the theater was a tremendous revelation. There was just an amazing amount of detail in the original film that I had never seen in all of the times I had seen the film on TV. The most striking example of this is in the scene when the lunar lander was being lowered into the moonbase. On either side of the elevator there are numerous windows, none of which were truly distinctly discernible on TV. There were actors walking around doing stuff and video screens displaying changing information while the lander was descending, all of which lent an extra air of reality to the scene. No doubt Stanley Kubrick went to a lot of extra trouble to add that in, knowing that people were going to be able to see it and that it would make the scene look just that much more realistic.
All that was nice and all, but I had my doubts that even HD would be able to present as much detail as that.
Turns out, I was wrong.
Just on a whim I decided to watch 2001 via Netflix Watch Now on the TiVo. Our Internet connection is good enough that we pretty routinely now get the highest quality streams available.
The stream they're showing now is every bit as nice as what I saw in the theater that day. All those details are clearly visible on our 50" TV from 8 feet away.
In hindsight, it should have been obvious to me. All you need to do is watch a little bit of an NFL game in SD and then HD to see the difference. It's not subtle. Not even a little.