A few months ago, I finished reading a book called Droidmaker: George Lucas and the Digital Revolution.
In the book, it's explained that Lucasfilm would demo its proprietary EditDroid editing machines using footage from Return of the Jedi, specifically the Luke/Yoda scene on Dagobah. As a result, they always had the most attention at conventions or trade expos. That footage, approximately 30 minutes worth of it, has made its way online via
this Facebook page. The Facebook page seems to be releasing bits of the footage at a time, though.
The footage is interesting for its alternate lines and a revealing look at how the scene was made. Thought this would be interesting to some of the die-hards around here.