Would need to check stats but do wonder if prior to the advent of TV money if it was less common for the champions of the various euro leagues to also win their countries main cup competition (ie 'the double, or trebles) therby qualification for the ECWC had more status.
Its demise was well underway when i got interested in footie but i do remeber thinking it was 'cheap' for the scottish cup runners up to get into it but then again Ive always thought it is 'cheap' for the majority of teams im the champions league to not be actual champions and in some cases to never have even won their domestic leagues.
I did only skim through that video but the section with the dons in it is fairly patronising and dare i say it ignorant of world football at the time. Dynamo Tblissi were one of the better teams in the USSR and had knocked liverpool out of the european cup only a couple of years before.
Of course that doesnt fit into the 'underdog' narrative