ELT stands for Emergency Locator Transmitter.
Les Fleurs du Mal or Flowers of Evil is a book of poems by Charles Baudelaire. The poem that Red is reading at 04:23 is "À Celle qui est trop gaie" / "To One Who Is Too Gay" from Charles Baudelaire - Flowers of Evil.
The six poems by Baudelaire banned by the French courts mentions by Red are: "Lesbos" (Lesbos), "Femmes damnés" (damned women), "Le Léthé" (the Lethe), "À celle qui est trop gaie" (to she who is too gay), "Les Bijoux" (the jewellery), and "Les Métamorphoses du Vampire" (the vampire's metamorphosis). The judges argued that these pieces would "necessarily lead to the excitement of the senses by a crude realism offensive to public decency. I.e. too racy.