adywan said:

The Biggs scene in the hangar was shown on TV programs over here in the UK before the movie came out just with on set audio. I remember finally getting to see the movie when it came over here and wondering why it wasn't in there. Back then i didn't have a Video recorder so i use to record everything that had any star wars material off the TV using my old hand-held tape recorder. I would listen to all these clips, interviews etc all the time and the Biggs scene was one of these. So it is possible that you may have seen this clip on TV

Sounds like it might have been part of a presskit for tv stations. Or perhaps a BBC crew visited the set?

There have been old 16mm clips on Ebay in the past with markings indicating they were for U.S. tv stations to use for reviews of the movie.