That will happen here in the U.S. at some point. It pains me to write that, but I believe it will because it’s just not possible to monitor everyone. We have been very lucky up until this point although that does not make the victims and communities that have suffered attacks feel any better.
If ISIS suffers defeat in Syria (or when they do) you will have the architects of what you just posted a video of traveling around the world. These are not the misfits trying to puzzle out how to do something in an online magazine or chat room - these are the ones that know what they are doing.
Them boys had some professional help there. Wonder if the cars were driven by suicide bombers ? Syria is such a mess. Professionals and suicidal religious nuts. We will probably see those scale of attacks in Europe soon. Heck the one recently in Baghdad killed over 300.