Don Corleone, that isn’t a real testimony. At worst it seems to be a late report of somebody after Christ and not from a man living at the same time.
At seeing the style, it is probably a Christian text. I am not convinced. And most of the historians think this text was added by the monks when they copied the original… Nothing special, the monks always added (or modified or deleted) some or parts of the texts they copied to reinforce the faith.

About a film speaking of Mohamed, well, I saw a documentary on History Channel and I still waiting for the muslin unrest and riots. Again, the Muslim religion does not forbid to represent the prophet, but to give in a face. You can find representation of Mahomet, but without a clear face.

I did write about the Da Vinci Code and I still don’t see where the problem is. A guy, collecting here and here some legends and real fact (Dagobert did exist but according to the French history died of dysentery after a life of slaughter, greed and debauches), living 2 sons after him who will become the Lazy Kings, who will be kicked out by the Carolingians. The only real legacy of this king is a song written during the French Revolution (C’est le Roi Dagobert qu’a mis sa culotte a l’envers, etc).
We can also argue about the picture made of Phillip, the King of Iron, and the man guilty of the slaughter of the Templars. He wanted to unite the Kingdom, the Templar were a menace against his authority.
The alleged collusion between Phillippe and the Pope is a non sense; Phillip put limit on the power of the inquisition, he denied the Pope Boniface VII to be the “Imperium Mundi” the Emperor of the World. He built the Etats du Royaume, kind of medieval House of Representatives, based on the 3 orders; those who pray those who fight those of work, like the St Augustine’s doctrine. He sent his army to attack the summer palace of the Pope and accuse this one of heresy. Boniface died few weeks after and the Popes will live in Avignon for some time.
He forbid private wars, free the serfs of the Royal domain, limit a right of justice of the land lords, he gave the right for all the serfs of France to buy their freedom. He created the Bourgeoisie du Roi, the bourgeoisie of the King which gave the right to a person or a town to become a direct subject of the King.

The endorsement by the Da Vinci Code of all the clichés and his lack of real knowledge of the ACTUAL French Society (never heard of the first name of the French Police Officer) made me doubt of the reality of his expertise.
However, as I said before, that made me to go for the Gnosis and I read a lot about the Gospels, St Irene and all the others.