Video from 2009. I have no idea how accurate this reading is (1). According to Wikipedia, "[t]he thesis of the book is that the text of the Quran was substantially derived from Syriac Christian liturgy, arguing that many 'obscure' portions become clear when they are back-translated (2) and interpreted as Syriacisms. While noticeable Syro-Aramaic influence on the language of the Quran is undisputed in scholarship, Luxeberg's thesis goes beyond mainstream scholarly consensus and was widely received with skepticism in reviews."
(1) One archaeologist reviewer quoted by Wikipedia describes the book as "almost unreadable, certainly for the layman. One needs knowledge of eight languages (German, English, French, Latin, Greek, Hebrew, Arabic and Syriac) and of five different alphabets (Latin, Greek, Hebrew, Arabic, Estrangelo) to comprehend the book fully."
(2) "Back translation involves taking the translated version of a document or file and then having a separate independent translator (who has no knowledge of or contact with the original text) translate it back into the original language," according to Language Scientific.
There's no reason why the Koran shouldn't be subjected to the same critical analysis used to study other ancient texts, the Bible included, but this particular interpretation was obviously explosive - so dangerous, in fact, that the author felt he had to use a pseudonym to protect himself from violent reprisals.
According to the New York Times (2002), "Christoph Luxenberg [pseudonym], a scholar of ancient Semitic languages in Germany, argues that the Koran has been misread and mistranslated for centuries. His work, based on the earliest copies of the Koran, maintains that parts of Islam's holy book are derived from pre-existing Christian Aramaic texts that were misinterpreted by later Islamic scholars who prepared the editions of the Koran commonly read today."
I'm passing this on because I'm interested in old manuscripts and I'd never heard of this particular controversy before. I wouldn't be surprised to learn that there are all sorts of problems with modern and even early medieval translations of the Koran, but I'm not competent to make a judgement one way or another. If you have to know eight languages and five different alphabets to understand the argument, I'd say that this whole subject is even more obscure and impenetrable than the study of mistranslations in the Bible.