Update: the passage in the original movie of
Fahrenheit 451 was from
David Copperfield (which I have since read). The passages read in
Gone with the Wind by Olivia de Havilland who just turned 102 are also from
David Copperfield. The presumable reason is that MGM had filmed
David Copperfield a few years earlier, whose sets were I believe among the many burned in the famous fleeing Atlanta scene so it was chosen over
Les Miserables which was what was being read in the book. Here is a meme of "Dover Beach":