The file refers to the 19th episode of the fourth season (specifically Part 2, the "Calamity Arc") of Is It Wrong to Try to Pick Up Girls in a Dungeon? . Episode 19: "Colosseum (Arena)"
Bell and Ryuu must cross the Colosseum, a massive area where monsters respawn infinitely regardless of how many are defeated. It is so dangerous that even high-level groups like the Loki Familia typically avoid it. DanMachi_Saison_4_episode_19_VOSTFR.mp4
This episode is a critical turning point for Bell and Ryuu as they struggle to survive the 37th floor of the dungeon. The file refers to the 19th episode of