Shock effect to promote a film. Does it work? The first and most recent one to promote the horror movie Devil’s Due ... Right in your face! The second one is a bit older to promote Carrie ... A bit nicer.
But does it work? The only positive effects I can see is the amount of YouTube viewers. And a couple of almost heart attacks. Do they have to ask permission of the 'victims'? I guess so. Well at least they have their one minute of fame.