Not quite what you are looking for, but perhaps this patent link may provide some inkling as to what do me manufacturers were up to? Note the links to various company patent applications at the bottom.
http://www.google.com.pg/patents/US3775178
I worked in videotape in the 70’s and have not (did not) hear that story. It always seemed to be about price. If the company bought a batch of tape and in practice it was found to be defective, them the manufacturer would usually replace the entire batch. It that didn’t work out the company generally went to another manufacturer. I don’t doubt Gulliver’s story though, it was a cut throat business with the salesman on commission.
Don’t recall we ever actually used BASF - can’t picture a reel with a logo on it. We used a lot of Scotch, Indeed I still have a Scotch reel with the foam protection on the inside of the reel’s surface, I have converted it into a clock and it sits very nicely on the wall of my study. Handsome or what!