I believe the videos are real , I heard a good theory before about why ISIS has released these last 3 vids the way they have, why they haven't showed the actual full beheading. It all for maximum effect and so its played on TV. If you ever seen other AL-Qaeda/Taliban beheading vids there usually VERY long 20-30min , they have Islamic music playing throughout the WHOLE thing, and the guys in the vid talk Arabic the WHOLE time. Those vids were NEVER played on TV, the most we would get was a screen cap, which for most ppl is

.
With these ISIS vid, there very short 3 min or so. There is NO Islamic music/text playing and they have had a clear speaking , British accent having guy does the beheading. If you watch CNN & the other new stations they playing these vids they play it pretty much up until he point where the guy puts the knife to the hostage neck , and the repeat the vids over and over . This never happened before, again that = maximum psychological effect