Ann Hornaday, the Post's movie critic, had an article about video on demand, noting the movement of movie watching from the theater to the home theater. It fits with another article I read about how fast movies are in and out of theaters.
Back in the day (of my youth), the big movies came and stayed, and we watched in crowds. Sometimes a good movie would run for months and months. You knew if you didn't see it in the theater, you wouldn't see it.
Then came TV, and sometime after good movies started being shown on TV, but only every 10 years or so. Gone with the Wind on TV was a big event. Of course this was all on broadcast TV, one of the 3 networks would boost viewership by broadcasting a notable movie. Gradually though more and more movies went to TV; just as gradually UHF stations popped up and cable TV started making its inroads. And now, of course, movies are available 24/7 through many media.
Back in the day we had communal events, not only big movies but big prize fights, big political conventions, big World Series, big novels. And everyone (i.e., people on TV and in the newspapers and the periodicals) would talk about it. There was a sense of a national community, although in retrospect some parts of the nation, such as the South, might have been left out.
Today it seems that the cultural landscape is flatter, there's no big peaks, fewer unifying events. 9/11 and the mass murders, McVeigh, Columbine, Holmes, et.al. may remain but not much else. There may, however, be a bunch of smaller events: parents seem to find community in following their kids activities much more closely than in my day, and there are more activities now than then.