It's interesting thing how easily people can be manipulated. It all was described in various marketing studies and perfectly applies to the whole world through mass media.
For example.
There are dozens of civilians being killed everyday in Ukraine by neo-nazis. There is lot more gruesome content in that war on daily basis than in all ISIS beheadings combined. Yet noone cares.
There was devastating landslide in Afghanistan at last spring. Like 2000 people were killed and more than 10000 were affected by. The next day it is forgotten, wiped off from the news by avalanche of new propaganda. It wasn't even most discussed story on the day of accident.
But once largest news media have started to post beheading videos once a week, here you are, jumping around, cursing muslims and ready to justify any aggression against any middle east country. The finger has been pointed. Go!
The most interesting part is that there is no need to get everyone's attention, the small, but loud percent is enough to start a revolution or to start bombings. And it works on international level. At highest point of media control you don't even need people backing. When each newspaper and news site posts the same message, it's like all world is in attention and agreeing with it.