OpenGameArt.org
the journey begins (nescaline & famitracker remix)
Credit line
"the journey begins (nescaline & famitracker remix)" by Baŝto licensed CC0: https://opengameart.org/content/the-journey-begins-nescaline-famitracker-remix Author's attribution notice: Igor Gundarev and Basxto
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.