Froggy, I want to carry on this conversation--I think it's really important--but I have to leave the screen for a bit. I'll be back later.
Meanwhile, I'd appreciate it if you (or others) could address this question, it's a genuine one:
I know you are trolling but I'll have a stab at answering this although I am not an Isis supporter so may be talking bollocks.
I think there is no single reason why they do it but here are some of the main ones. Bear in mind this is from stuff I gave read over the last few days and my thoughts on that so imo shouldnt be taken as gospel
I think 'revenge' is a reason but a very, very small part of it, I do think that the salafist narrative of 'good' 'muslims' (a very small part of the worldwide faith) vs 'bad' everyone else (including shias, 'apostates' etc) plays a significant part in why people join ISIS, coupled with the war/martyrdom rhetoric and apocalypticism (their magazine's title alludes to armageddon for example) I don't think that salafism can be pinned on western imperialism since the overwhelming majority of attacks by salafist groups are against muslim civilians.
I think the orange jumpsuit thing is more a message to the siddique khan type deluded sapzs who are considering joining, i think it's partially a recruitment device, and partly done for 'aesthetic' reasons, to attract those who aren't just upset about the suffering of muslims throughout the world but are drawn to and attracted to violence, the kind of people who in a different setting would have hung swastikas flags on their walls rather than ISIS ones.
I also think it's done to terrify their enemies but also to terrify people thinking of deserting into staying - I think another reason why this video has been released now in the aftermath of kobane is to say look we're still here and dont give a fuck what you think.
In other words I dont think there's one reason why they release these videos and do these things. I think there are several.
Also remember that this was one of the reasons for Zarqawi's original quarrel with OBL and the al-qaeda leadership who were unhappy with the beheading videos they were putting out because they thought it would alienate mainstream public opinion in the middle east, these guys are trying to say they literally do not give a shit about public opinion.
This is probably all bollocks but these are just some of what i think the main reasons could be.