The interest of this garrulous, convivial documentary creeps up on you by degrees: a study of secondhand and antiquarian booksellers in New York City. This was once a clubbable – and very male – profession that hardly changed for centuries, run by a mole-tribe of eccentric, tweed-wearing guys who were irritated to be beckoned from their chaotic shelves of old books by someone cheeky enough to want to buy one. (I myself find something necrophiliac and stifling about used-book shops like this, but this film sold me on them, a bit.)

The business was upended by the internet, which brought unexpected calamities and benefits. The market for mid-range 20th-century first editions – ie a mint-condition copy of Ian Fleming’s From Russia With Love – collapsed because their rarity value plummeted: you could just type in any title online and find it. (The film doesn’t mention it but there were once firms akin to private detective agencies advertising “out-of-print book searches”, who were allowed to charge you even if they didn’t find the book.)

But this upset has caused an upsurge of interest in manuscripts, annotated editions and ephemera collections, conferring archival and financial value on items that had previously been disregarded, and which has been a boost to studies of the cultural lives of women and people of colour, helping to bring these subjects in from the margins. Now the business is not just men only, it is younger and more diverse (though no one uses the hip word “curators” – it’s “collectors”) and they are convinced that reading hasn’t been killed off by Netflix.

The sharpest interviewee is the bibliophile and collector Fran Lebowitz, who supplies a couple of insights. “You know what they used to call independent bookstores? Bookstores!” And also: “When I first came to New York it was called the ‘art world’. Now it’s the ‘art market.’”

• The Booksellers is available on digital platforms from 29 June.