In other words: The Yazdgerd letter to Omar exists but what we read here was a spiced up version of the original text which should be read with caution.
2009/12/3 ardeshir farhmand
There was indeed a letter from the noble Yazdgerd to omar the third caliph. however, this letter on youtube is NOT authentic. Yazdgerd did advise omar that the persians worshipped, the One and only GOD, Wisdom; and that his symbol was light in the physical creation. He told him to go back to his lizard and snake infested wasteland for his ways were ungodly and murderous. He also talked about the adoration of elements, the love of animals, and persian warrior women in his letter, and reminded omar that arabs were ashamed of their women and buried them alive. there was nothing in the new teachings that contained a wiser or better message that did not already existed in the ancient religion.
furthermore, the local nobles and many priests were tired of central sassanid gov, and the heavy taxes. They decided to sell their faith and country, thinking that they can strike a much better bargain with the arabs. as we read in this great preface to the bun-dahishn"
"Owing to the coming of the Arabs to Iran-shahr, and their promulgation of heterodoxy and ill-will, orthodoxy has vanished and fled from the magnates (Magi), and respectability from the upholders of religion; deep wonderful utterances, and the proper reasoning of things, meditation for action, and word of true reason, have faded from the memory and knowledge of the populace.
"On account of evil times, even he of the family of nobles, and the magnates (Magi) upholding the religion, have joined the faith and path of those heretics; and for the sake of prestige, they have defiled, with blemishes, the word, dress, worship and usages of the faithful. 4. He too, who had the desire to learn this science and secret, could not possibly appropriate them, from place to place, even with pain, trouble and difficulty."
The following scenes from "lord of the ring" could have been a replica at what happened to the zoroastrian priesthood and nobility.