The documentary was filmed over three years. Among those interviewed were his two ex-wives, Kris Kristofferson and Robert Duvall.
As opposed to the one-too-many comma problem.
Like Mr Weintraub, I don't understand why the final serial comma has fallen out of favour.
It is also known as the 'Oxford comma'.
The Oxford Style Manual, 2002, Chapter 5, section 5.3 Comma
For a century it has been part of OUP style to retain or impose this last serial (or series) comma consistently, [...] but it is commonly used by many other publishers both here and abroad, and forms a routine part of style in US and Canadian English. [...] Given that the final comma is sometimes necessary to prevent ambiguity, it is logical to impose it uniformly, so as to obviate the need to pause and gauge each enumeration on the likelihood of its being misunderstood – especially since that likelihood is often more obvious to the reader than the writer. (pp. 121–122)