I think that the black hooded figure represents the burdens/responsibilities of adulthood. In the beginning, you see the boys having fun inside the fence which is labelled "Youth", implying they are still in their youth. Then, Suga climbed over that fence, which signifies his transition from youth - and he walked towards the black figure, which as I said might represent the burdens of adulthood. Suga greets him, but sets him on fire with his music - i.e Suga refuses to succumb to the burdens, he wants to burn them away with his music. That even when he is past his youth (climbing over that fence), doesn't mean he can't be young forever (immerses and have fun in music)? I don't know if I'm making sense. pretty cool not mine found it