You're recording a funny Minecraft video testing a Minecraft mod called "From The Fog" which add's Herobrine back into Minecraft, in this mod he is programmed to stalk you and creep on you when you are not looking, but when you see him, he dissapears, in case of the stalking sightning, he dissapears eventually getting out of sight and dissapearing, you get on your world and start recording, knowing that he is coming, it's day one and everything is fine, but as time passes, it get's worse.