Link to the music video: https://www.youtube.com/watch?v=NU9JoFKlaZ0&t=104s

The album American Idiot was released on September 21, 2004, and is now around 20 years old

Twenty years has gone so fast

Wake me up when September ends

What the song was about:

One of the songs in American Idiot, "Wake Me Up When September Ends", is not entirely related to the album's central narrative.[6][7] The song was inspired by the death of lead singer Billie Joe Armstrong's father in September 1982.[5] On the day of his father's funeral, Armstrong reportedly ran home, locked himself in his room, and when his mother came to check on him, he told her to wake him up when September ended,[8] and held onto the song title for several years after.[9] In an interview with the Howard Stern Show, Armstrong said that he initially avoided writing a song about his father for years, until he "[had] a breakthrough" and created "Wake Me Up When September Ends" in his honor.[

What the music video was about:

Bayer envisioned the video as a mini-movie,[50] wanting to create something unlike other music videos that he felt were predictable.[49] Bayer brought the idea of an Iraq War-themed video to the band after interviewing soldiers who had signed up to fight after being persuaded by a television advertisement.[51] Bayer also said that he wanted the music video to be more political than the album's other music videos, saying that he "wanted kids to talk about the war," and felt that MTV had not spread awareness of the conflict and its consequences on soldiers.[13] Although it was not the song's original meaning, Armstrong felt it was appropriate.[52] Bayer and his crew spent a month casting actors for the roles and conducted rehearsals, which was uncommon for music videos.

https://en.wikipedia.org/wiki/Wake_Me_Up_When_September_Ends#Music_video