I have a theory. It might have been a player in one of herobrine's dungeons looking for rewards.
there is a chance he brought his wolf with him too explaining the barking.
the play finds an ore and tries to mine it, hears his wolf barking at herobrine and looks back to find him, the player runs, afraid of herobrine. he then goes through arrow shooting dispensers and falls in a hole breaking the disk the being killed by herobrine, saying his last words, herobine.
the part where the flint and steel sound is maybe the player lit torches to see