OpenGameArt.org
1-2-3-4 (Guitar)
Credit line
"1-2-3-4 (Guitar)" by Pro Sensory licensed CC0: https://opengameart.org/content/1-2-3-4-guitar Author's attribution notice: just include my name, Alex McCulloch. Attribution appreciated but not required.
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.