OpenGameArt.org
MML Blues
Credit line
"MML Blues" by Varon Kein licensed CC-BY 4.0: https://opengameart.org/content/mml-blues Author's attribution notice: Attribute as Patrick de Arteaga and a link to patrickdearteaga.com.
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.