Slender Man
 

can anyone tell me the story behind marblehornets and slender man?

Marblehornets didn't make up the slenderman story I don't think.
Slenderman is completely fake.
No, "Picture evidence" would make sense, because slenderman was actually made up for a contest by some kid.
A completely falsified monster, yet people still claim to have seen it.
Marblehornets is just a youtube show based on slenderman, and a good one at that.

i heard that one of the guys in marblehornets dissapeared... and the other guy burned the original tapes. whats that about?

Its about shock value and views :P

Slenderman = Photoshopped version of the Trololo guy...next time you see a video about it, just think of the trolol song XD you won't have to worry about it ever again.