Islam is the real deal

[Angrboda]

Imam Fakhr-ud-Deen Ar-Razi states,

When Zul-Qarnain reached the furthest west and no populated land was left, he found the sun as if it sets in a dark spring, but it is not in reality. The same when sea traveler sees the sun as if it sets in the sea if he cannot see the shore while in reality it sets behind the sea. (Ar-Razi, At-Tafsir-ul-Kabir, Volume 21, page 166)

Sunan Abu Dawud 3991—Abu Dharr said: I was sitting behind the Apostle of Allah who was riding a donkey while the sun was setting. He asked: Do you know where this sets? I replied: Allah and his Apostle know best. He said: It sets in a spring of warm water.

This hadith has nothing to do with Zul-Qarnain and "how things appeared to him."  Muhammad is saying it sets in a spring of warm water.  Your explanation doesn't work.  (Apparently you didn't watch the video or read the article.)