Now HyperScope has been released, don't miss Brad Neuberg's great Screencast of Douglas Engelbart's Augment System
How much was SdiDesk influenced by Engelbart? Directly, not so much. But indirectly, obviously a lot. My direct influences were wiki, the Smalltalk environment, Emacs, HyperCard and the web-browser. Obviously, all, heavily indebted to Engelbart's work.