Oh they are far worse than communists.  They are fanatics in the worst possible meaning of the word.  Alan Henning was, from all accounts, a great sympathiser with the Muslim cause and was I believe considering becoming Muslim.  They have killed loads of Muslims already and of course many Christians.  They consider most of the world kafirs - unbelievers and they will literally stop at nothing to kill kafirs.  We have all got used to the term jihad now but its meaning is deadly.  Their mission in this country to bring in sharia law and if they manage it then we really have no conception of what that would mean.  And that's of course just this country - their mission is worldwide, and they are doing quite well.

it's easy enough to edit vocals over footage that has been shot a while ago - I'm with Fluffy - I don't think they hold these hostages long before they kill them 

Some other countries pay ransom and get their people back, so I don't think they are killed before we are told.

Well.. I'm not going to watch the video to judge.   Either way... evil bastards. 

My gut is they don't kill them right away, col     No bargaining chips if they're dead anyway......

I think the first two may have been murdered together and the second video released at a later date, evidence suggests that they were. 

I'm with Kaff's on the Alan Henning one, intelligence would know if the video had been dubbed and these people are evil but not stupid. Also, we have seen a video of John Cantlie alive and reading from a script. 

but they also know that the US and UK won't pay - they probably keep them long enough to see if the families will raise funds privately hence why there is communication between ISIS and the families but I'm guess when they know no money is forthcoming they kill them to lessen the amount of times they have to move them around.