pierre wellner’s 1991 digital desk is a seminal piece of human-computer interaction research, but it’s also a pioneering video. in today’s interaction world, video documentation is essential to show how a dynamic, responsive system works. in many ways, videos are the documentation media best suited to interaction design. as wellner’s video demonstrates, it’s not necessary to build a working system in order to make a compelling and influential video. while he shows his working prototype for a few minutes, the most radical aspects of his project are mocked up for the camera – the so-called ‘envisionment.’ sharing these mock-ups could serve a valuable role to pre-evaluate interaction ideas before they have to be built – or to document ideas too new to be built, and inspire future work.