Doug Engelbart's 1968 Mother of All Demos

HN uses it as the go-to reference for how many modern computing ideas, collaboration included, were demonstrated in 1968.

Highlights from Doug Engelbart's December 1968 demonstration at SRI, the first public showing of the mouse, hypertext, windows, real-time collaborative editing and shared-screen teleconferencing. This is a roughly six-minute condensed version of the full demo.