Featuring various members of the movie's cast who are welcoming new students to Panem's Academy, the video is chock full of eccentric costumes and vaguely Masonic-looking iconography.

Source: https://comicbook.com/movies/news/the-ballad-of-songbirds-and-snakes-promo-video-welcomes-you-to-the-academy/

In both the original saga following Katniss and the recently released prequel, we learn were designed to strike fear into the heart of Panem's twelve districts, punishing them all for a war that most weren't even alive for.

Source: https://collider.com/the-hunger-games-horror-franchise/