The novelist John Irving made that observation years ago about the VCR, and each generation of video technology brings watching and reading closer together, making video more private and more under the user's control.
Until recently, books were unlike video in that they private, portable, and under the reader's control. When you're reading a book, you're alone. Even if you're around other people, they're not participating in the experience.
Books are portable. They generally weigh very little, so you can easily tuck one under your arm or in your pocket, and take it anywhere.
And books are completely under the reader's control. You can start them where you like, go backwards, go forward, read faster, read slower, or repeat passages at will. You can put them down and come back to them later and pick up where you left off.
Until recently, movies and TV had none of those qualities.
They weren't private: You see a movie in a theater, with an audience. You watched TV at home, on a big box, and most people didn't live alone. Often, people watch TV in company.
They weren't portable. Movies, of course, required a whole building -- and a big one at that -- for their display. TVs were piece of furniture, often wooden cabinetry.
And the viewer couldn't exert much control over what he was watching. Movies and TV started on schedule, and the viewer couldn't rewind, fast-forward, jump ahead, or pause viewing.
But then came the VCR, and video started to get to be more like books, observed Irving, author of The World According to Garp and the novel Cider House Rules and the movie screenplay. You could watch video when you wanted, stop and come back later, go backwards and skip ahead.
The advent of affordable portable DVD players in this decade made video something you could carry with you.
And now, with the iPhone -- and other video-enabled phones -- you can put video in your pocket, just as you can do with a paperback novel.
It'll be interesting to see how the medium of video evolves to fit the iPhone and other portable and pocket-sized players.
YouTube has given us the three-minute video; that seems to be the sweet spot for how long people will sit still to watch video on their computers.
Pocket-sized videos can be longer. You can sit in a comfortable chair and watch it at your leisure, like reading a book. With the iPhone, I find I even hold it like a book. So, as regards length, an iPhone video will be more like a conventional TV show or movie.
Of course, the screen on the iPhone is tiny. I wouldn't want to watch an epic movie like Titanic, or even a highly visual TV show, like CSI: Las Vegas, on my iPhone.
I expect we'll see new storytelling techniques evolve to fit this new medium, to fit the constraints of the small screen.