Thanks for sharing the link to the video, this is the fourth video I have seen of ISIS in combat, and it only adds to the assessment of the analysts quoted in the article. Again we're assessing relative combat effectiveness, so I disagree with you that they couldn't stand up to a real Arab Army anywhere in the Middle East. The Syrian Army is quite good relatively for the region, and ISIS does moderately well in stand-up battles against them.

0:55 the automated command, control, computers, communications, and intelligence (supported by a drone) is relatively impressive. Probably something we'll see more of around the world due to the availability of this technology.

starting around 1:35 the use of mostly conventional crew served weapons is impressive. Acquiring them in battle is one thing, employing them effectively is another. They have done both. Results starting around 6:40, with numerous IA vehicles destroyed including at least one tank.

I tried to find it, but I suspect it was removed from the internet , there is one video that is impressive showing ISIL storming an occupying building. They took some hits in the way in, but in a disciplined manner persisted with the attack until they were successful.

People much less well trained and equipped made life difficult for our guys in Fallujah, so I wouldn't underestimate the challenge. No doubt we can defeat them, but at times it would be become a slug fest.