The info I got many years ago is this;
During the Saturday show (31st August), members of the audience were given tickets to attend the Arena the following Monday (2nd September) daytime for the filming of the video for the Heavy fuel single.
It sounds logical, but now read a complete different story, which was HIGHLY interesting to read. Maybe they recorded parts during a special daytime show and parts during the actually concert? Wish there alwas a bootleg of 2nd September 1991 now!
Maybe stuff was filmed through the day with a "crowd" but not used in the final video? All of the clips prior to the show seem to be just in the empty arena and then it's pretty clear which shots were taken at the live show, and which were done prior during the day.
Even a bootleg video probably wouldn't reveal too much - as I said in my original post, the only thing I noticed during the show was when a cameraman appeared on the stage from time to time, obviously just getting little clips of each band member which would be stitched together in the final video (I was hoping that maybe the show was being filmed similar to the Wembley 85 release, but once I saw the HF video on TV I realised what it must have been for). There was obviously at least one more camera filming from the back of the arena but I didn't see any others.
Other than that, the only difference to the actual show was the fact that HF was played last (and I didn't even know that that was unusual at the time). They played the usual encores (MFN, SMU, BIA) and then when they came out again MK just said something about "doing a bit of filming" before they played HF. Even during that song, the only noticeable thing that happened was the woman running onto the stage, but that happened very quickly. Probably if you were right at the front you might have seen them setting that up, and maybe also recognised Randy Quaid, but we were a little way back and on the opposite side of the stage (in front of John).