Interesting video - but I would take exception to one of the speaker’s assertions. He claims that one factor that weakened the Byzantine Empire was the Bubonic Plague - but the Arab expansion began in the 7th Century, while the first European appearance of the Bubonic Plague was in Crimea in 1350.
With that possible exception that may need clarification, he is pretty much 100 percent correct.
It is hard to argue with the facts.... let alone the cumulative facts over the last 1400 years.
The Black Death and the Byzantine Empire (3:32)
http://www.history.com/videos/the-black-death-and-the-byzantine-empire#the-black-death-and-the-byzantine-empire
And...
The most famous plague outbreak swept through Europe in the 1300s. Dubbed the Black Death, the disease killed more than 25 million peopleone-fourth of the continent's population. The nursery rhyme "Ring Around the Rosy" is traced to the plague's rose-colored lesions and deadly spread.
Earlier outbreaks also decimated Europe. The Justinian Plague claimed as many as a hundred million lives in the Byzantine Empire during the sixth century A.D. "
The question remains...why isn't this information more widely known, especially in our schools?
/rhetorical