Media File source can't open in Media Player

Hello, I’m trying to add a jukebox system in my game with this tutorial : https://www.youtube.com/watch?v=d3sevd7c0Hw&t=923s, it works in a blank project but in my project I don’t know why, my media player tells me the error that it can’t open the files.

LogElectraPlayer: Error: [000008D027F36600][000008D100CD5310] ReportError: “error=0 in Player: code 2, “Could not determine stream MIME type””

I did create a “Movies” folder in the “Content” folder of my Unreal project where I added my .wav files