No, I think the Islamic State is a somewhat real threat. Granted, one must realize that America is also essentially responsible for its existence by creating a power vacuum with the deposition and subsequent execution of Saddam. It is because of them that ISIS could flourish (previously they were a small subset of Al-Qaeda).

They have time and resources to produce Hollywood-quality videos because they have money and contacts. It is probably very easy for them to get someone to buy a Hollywood-caliber video camera - RED ONE, Arri Alexa, etc. Even your standard $700 DSLR could do the job - with a Western credit card or a Turkish address. They can also go on the internet and (by most intellectual property laws, illegally) acquire a copy of any decent editing software like Photoshop or Premiere Pro. Even Windows Movie Maker can be fairly competent.

They ended up bringing the world into it because of the escalation of their actions. They threatened to eliminate an entire ethnoreligious group, kidnapping Westerners and basically TRYING to incite the wrath of the Western world.

That is why they do what they do. And that is why they probably won't be any sort of credible threat in a year or so, because their actions will be their downfall.