The Bible is not a science textbook
By the way, to be clear, I am not disagreeing with your post, I am merely lamenting the extreme insensitivity of whoever made that video towards Eastern Orthodox Christians, who have never taught or emphasized a flat-Earth cosmology. The monk depicted is shown wearing the Great Schema, which is often given to elderly monks and nuns who are approaching the end of their lives due to illness, and otherwise is given only to the most extreme monastics, and monks who take the Great Schema are no longer eligible to become bishops, but are dedicated purely to a life of prayer and of such work as is needed to support them, since our monks are not mendicants, unlike for example the Buddhist monks (who actually copied much of their modern organization from Christian monasteries that used to exist in China, Tibet and Mongolia until the 12th century, when the Muslim warlord Tamerlane decided to kill off all of the Christians in those lands and in Central Asia and Yemen, a mission completed by his many sons. And I am aware of no national memorials to these martyred Christians, but there is a spectacular shrine to Tamerlane in Uzbekistan, where he is regarded as a national hero (despite not actually being an Uzbek but rather being a Muslim of generic Central Asian ethnicity, but the Muslims never seem to let the facts get in the way of their beliefs, except for the sake of expedience).
On the subject of Islam by the way, amusingly, unlike anyone in our Bible, Muhammed actually did teach explicitly the world was flat, and went sofar as to argue that the disappearance of ships over the horizon was an optical illusion. Indeed the Quran contains a bizarre episode where Alexander the Great, who the Muslims also regard as a prophet for some unfathomable reason, travelled as far West as possible and encountered the sun resting at an oasis at night, where the sun and Alexander the Great sort of chilled and had a conversation before the sun had to return to the East to resume his duties. And thus there are Muslim fanatics who insist on the world being flat, and they do regard the Quran as being not only infallible but uncreated.
However, conveniently, they then disregard this where necessary, for example, in order to operate their vast airline businesses (such as Emirates, Qatar Airlines and Etihad), which would not function if the Quran were what the Mullahs say it is.