The Mother of All Demos, Douglas Engelbart (1968)

If you watch only one recording here, make it this one. On December 9, 1968, at the Fall Joint Computer Conference in San Francisco, Douglas Engelbart and his team showed the mouse, linked hypertext, on-screen text editing and a live video link to colleagues in Menlo Park, all in a single session. Almost every interface on this list borrows something from it. It is long and grainy, so dip in by topic: the first look at the mouse, the jumps between text and graphical views, and the shared screen with faces superimposed over the work. Keep in mind that this was a research system, not a product you could buy; the later entries show who turned it into one.