For this challenge, we are given a Youtube link, https://youtu.be/erECF4vlKQ8. Opening the video reveals some audio and we are asked to find the song name.
A good tool for challenges like these is the mobile app, Shazam. Pressing the Shazam button brings you to a new screen, meaning that the app is listening and will find the song and its details.
When we play the Youtube video and have Shazam listening to the audio, we get a screen saying that Shazam can not find a song matching the audio.
Listening to the audio, we realized that the song was reversed, so we looked for tools to reverse the audio of a Youtube video and found Kapwing.
Link to the reversed audio: https://www.kapwing.com/videos/5e7ed97745d0350015dba5e1.
Result: When we play the new, reversed audio and have Shazam listening to the audio, we find out that we are listening to The Hills by The Weeknd.
Flag: riftCTF{The_Hills}