That's bound to make the sites' executives a little nervous, and the video includes footage of purported account hijacks in an attempt to show that this is more than just tough talk. However, it's unclear if there's any meat to the threats. It's easy to produce a video, but it's another thing to mount a real attack. Moreover, the very existence of the clip suggests that the account takedowns are proving effective -- there wouldn't be pressure to respond if ISIS could simply shrug off the loss and move on. While it's no doubt important to take the threats seriously, they may say more about the extremists' hurt pride than anything else.