A qiraa is a mode of recitation. A recitation is orally transmitted by one reciter to the next going back to the prophet himself. That is why the fame and spread of a qiraa is in itself testimony of its authenticity and the less it is used the more its legitimacy can be questionned. One cannot create a recital in a vacuum and impose it on the masses, passing it off as authentically received from the prophet. This has never hapenned and never will. The process by which a particular recitation imposed itself was gradual, as it was transmitted from teacher to student. Had there been other mass transmitted qiraat than the 10, it would have been inevitably known. Their spread and use among the Muslims in itself would have provided a major argument for their authenticity, as with the 10.
Sometimes one and the same teacher reciter, taught a different qiraa to a different student. That is nothing new contrary to that youtuber's pompous tone.
Hafs quoted Aasim as saying that the qiraa he taught him was that of as-Sulami, from Ali ibn Abi Talib, from the prophet, while the one that he taught his other main student Shu'ba, was that of Zirr ibn Hubaysh, from ibn Mas’ud, from the prophet. That is why we find that, Shu’ba and Hafs, who studied under the same reciter Aasim, differed from each other in around forty places.
What is further remarkable is that there are "only" 10 readings while the basic script allows for many times more reading possibilities, with all of them making sense. This in itself is enough to dispel the notion that the 10 qiraat were due to a defective arabic script, rather than inherited by the oral tradition we already know to exist and is well attested. An evident example to corroborate is that of the skeletal m-l-k in surah fatiha read maalik or malik. The word appears in several other places where both reading could equally be applied yet the only place with divergent readings is sura fatiha. This is because the readers were not free to apply their preferences, they were constrained by the sunna of the qiraat. The Sanaa manuscripts have since confirmed this tradition on the qira'at.
(Nicolai Sinai)"Thus, the Sanaa Palimpsest would appear to provide us with an exciting glimpse at a moment in time at which the hegemony of the Quran’s standard rasm had not yet become fully established. This, it must be said, is in line with the general drift of the Islamic tradition, which reports that during the first decades after Muḥammad’s death a variety of quranic recensions were in circulation. Although none of the exact “companion codices” described by Islamic sources have yet been discovered in manuscript, the general types of textual variants ascribed to them correspond to the types of variants found in the lower layer of the Sanaa Palimpsest. 17 The latter thus lends credence to the idea that there was originally more than one recension of the Quran and that the Islamic literary sources preserve a broadly accurate view of the scale and character of textual variance between these different versions of the Arabic scripture".Among the aspects of the known variant readings confirmed by the most recent scholarly observations is the phenomenon of qira'at tafsiriyya/exegetical recitation. According to Hilali’s general characterization,
“[m]ost of the variations in the lower text include more lengthy text than the corresponding passages in the Cairo edition”.This has led the major works of Hilali and Sadeghi to conclude that
"the lower text of the palimpsest is derivative from the standard recension".Hilali further reflects exactly what the Muslim authorities have stated concerning the shaad qiraat. She opines that the authors of the palimpsest integrated interpretative passages into the text without clearly demarcating the 2 because they did not consider their writings to be transmitted to the general public. Their works were meant for personal use. Ibn al Jazari says that some companions would
“insert exegesis into recitation by way of explanation and clarification because they were endeavoring to ascertain the true meaning of what they received from the Prophet by way of recitation; they were safe from confusion [between the text of scripture and the explanations added to it], but some of them may have written it [the explanations] down together with it [the recitation].”
These Recitations were accomodating to the major dialects of the Arabs, thus leading to unifying the Arabic language, and validating all of its variations and subtleties. This not only allowed a faster spread of Islam but also solidified and preserved the language, as part of the divine pledge to protect the Quran. Had there not been approved recital variations, going back to the prophet's time himself, it would have opened the door to tampering with the text to adapt it to different dialects. It would have corrupted the meaning of the text. As time passed, the phenomenon of fame and spread of one religious, political center instead of another led in the Muslim world, movement of students and teachers led to some qiraat being supplanted by others more popular ones. Today the one most spread is that of Aasim through Hafs.
2:271 "If you give alms...yukaffir/this will cover up some of your evil deeds"while the Doori reading is
"If you give alms...nukaffir/We will cover up some of your evil deeds".Both readings perfectly complete eachother, with the latter saying Who will provide the covering (God) and the former saying through which action (charity). 9:66 is very similar with Hafs saying
"If we pardon/naafu a group of you we shall punish/nuaadhib another group"while Doori says
"If a group of you is pardonned/yuaafa another group will get punished/tuaadhab".Doori explains what the contrasting behaviors spoken of in the passage will result in (a group will be pardonned while another will be punished) and the Hafs says Who will grant forgiveness or inflict punishment. Another similar complementary example is 2:10 in Hafs
"a painful chastisement in what they lied/yakthibun"while in Doori it is
"a painful chastisement in what yukathibun/they gave the lie/they made a lie".Both readings come together and reveal that their lie is twofold, consisting in knowingly misrepresenting something that is true. One can give the lie to someone or something by exposing the truth about it, which is commendable. One the other hand one might give the lie to someone/something by inventing a falsehood about him/it, which is a twofold crime deserving punishment. Again in 6:115 Hafs
"And the word/kalimatu of your Lord has been accomplished truly and justly; there is none who can change His words"while Doori reads
"And the words/kalimaatu of your Lord have been accomplished truly and justly; there is none who can change His words".The singular kalima refers to God's word in the sense of his promise as amply used in the Quran while the use of the plural kalimaat in the Doori reading reveal that this promise is none other than the words of this book. A last example to corroborate is 43:23 Hafs
"He said/qaala: What! even if I bring to you a better guide than that on which you found your fathers?"While Doori reads
"Say/qul: What! even if I bring to you a better guide than that on which you found your fathers?".Hafs is quoting a prophet, but Doori explains that the words of this prophet were directly inspired by God.