Very nice. :)

Okay, my theory is that some random guy was in a mine with his dog, and was just mining when herobrine came after the dude and he starts placing torches, pulling out a map, and finally gets chased by Herobrine some more, heavy breathing, and lastly, Herobrine catches the poor guy and the disc breaks as he utters the name and dies.

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.

herobrine and maybe lighting

at the end of the disc you hear HEROBRIN

I think its a guy in a cave crafting flint and steel lighting a netherportal and then running from a ghast or zombie pigman or blaze Cuz in the next update they were adding the nether world

It is said he was chased by either

1. Herobrine

2. Enderman

3, Wolf (because you can hear barking noises

This is the story I made up about it: Brine, a 22 year old male, is stuck on a deserted island. He has few resources and decides to mine for some things. He clicks on his belt, tightens it and then opens a book to find out what to expect. He has a bad case of a cough. Suddenly, he hears the faint sound of ....something..... and immediately tightens his belt, closes the book and starts sprinting toward where he came in. He doesn't make it out, and is over taken by a Oreh. His eyes glow white, and gains the wearings of the first thing he sees: Steve.

i think a guy is getting chased by an ender man