What probably happened was MD was hired to come play at a festival.
Their rider include the agreement that no other stage would be live while they were playing. Management agreed to it and the deal was done.
Local Rap artist got his time on a separate stage cut short as he didn't go on stage on time nor was given the amount of time he thought he was going to get.
MG goes on, Local Rapper is pissed and decides he will retaliate against "The Man" who shut him down.
Local Rapper runs on stage disrupting the MD show, gathers attention to himself, and blames MD for all his problems.
Anyway, the truth is proabably somewhere in the middle. I am not a big MD fan, and if this is the type of venue they are now playing, then this is typical of what happens. The one thing I don't see when searching Google is MD complaining about QStock or the Disruptive Local Rapper.
Surprising to me, MD is being the professionals here.
Maybe the smell from the cooking fish was too much for the foreigners.
Maybe Disruptive Local Rapper had his time cut shut by management and he was pissed.
Maybe MD was being big princesses and caused all the problems.
Either way. I have no interest.
For your review. YouTube ->
Local Rapper Crashes Megadeth Performance