Exactly, it's a demo disc for the trade shows where Editdroid was shown off. The youtube video I linked to earlier in the thread was from 1984. The plot cat was well out of the bag by then.

Note the date on the disc label, 1983.

Even if they were rough cutting the film at Elstree, you have to take into account incompatible video systems, PAL vs. NTSC. Even if they brought a bunch of NTSC gear over there, would it work properly even with current converters of the day? I couldn't even get a hair dryer to work outside the U.S. once. ;)