it has more to do with the safety rules of the shooting range where the match is held, some ranges where i have been, it's not allowed to point a gun over the berm, because there are other shooting bays behind the berm or something like that, the most shooters wil get a dq when performing a reload, because most shooter are changing mags with the gun pointing with the barrel high in the air and over the berm.
it's like the same rule with grey tape, on the mobile bullet traps commonly used on indoor ranges, when a round penetrates the grey tape with full diameter or you miss completely you will get dq'ed, for violation of the safety rules, but this is nowhere to be find in the ipsc rulebook.
but in the case like in the video, i personally think that the stage shouldn't be set up like this, it was better to move the outer screens a meter further to the middle, shooting around barricades is difficult, exiting a position like that is even more difficult, and when exiting it's natural to point the gun a little to the outside away from the screen, in this case the margin was just to small to do that, and resulted in a dq, wich in my opinion didn't happen when the stage was build properly, it's not only the shooter wich has to be concerned about his/her and others safety, that's also a responsibility of the stage designer / builders.