Zarqawi has method in his madness
It´s a curious thing that if you kill a few people, you are a monster, but if you kill tens of thousands, you can still be a statesman, an honorable general, a hero etc. No doubt al-Zarqawi can be called a monster, but the fact is, the thing that disturbs people most in his actions are not the killings; his group has killed hundreds of people in bomb attacks, but these got far less publicity in western media than the brutal murders of hostages. The victims of bomb attacks are faceless and mostly non-western. The hostages his group has murdered are given faces by these videos, their helplesness and their suffering are not hidden, they are shown. This makes al-Zarqawi such a reviled figure. He doesn´t hide his crimes, he uses them as a propaganda weapon. His propaganda has then different messages for muslims and westerners.
If he would just make demands for the release of the hostages and then kill them in secrecy when his demands are not met, he would not be seen as such a terrible figure. After all, hostage taking and killing of hostages are nothing new in human history. And in reality, these kinds of public murders are neither. But in the past the audience was limited.
For example, let´s go to England during one of it´s civil wars in the 1140´s. King Stephen(1097-1154, ruled 1135-54), the nephew of Henry Ist(1068-1135, ruled 1100-35), was fighting against her cousin Mathilda, the daughter of Henry Ist, for the crown. During a siege of a castle of Mathilda´s supporter, the commander of the castle gave one of his sons, just a boy, as a hostage, for the time of a ceasefire, during which the negotiations for the surrender of the castle would be held. These were unfruitful and as the commander was not ready to surrender, the king decided to hang the boy so that his hanging could be viewed from the castle walls, which would show the determination of the king to take the castle, the helplessness of the defenders to do anything to stop him and how useless it would be for them to resist him.
This was nothing uncommon at the time. King Stephen had executed large number of men in the same manner. But for his undoing, he wasn´t ruthless enough. When everything was ready, the king couldn´t hang the boy, who didn´t understand his coming fate. The boy, William Marshal, lived and in his late years became the regent of England in 1216. Stephen in the end, after the death of his eldest son, made a peace with Mathilda´s son Henry(1133-1189) in 1153 and made him his successor in England. Stephen´s younger son was denied the crown and died fighting in France in 1159.
This kind of executions of hostages served the same kind of role that al-Zarqawi´s videos do. They just had a very limited audience. Nowadays al-Zarqawi has a global audience.