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":