I've been told that French tv has just finished showing a four part miniseries about young Voltaire.

Trailer

Wiki entry

Now if ARTE (= French-German tv network) should adopt it, I'd have a shot at watching, otherwise it's probably hard to come by. Stay tuned! The cast includes Philippe d'Orleans the regent, his daughter, Voltaire's buddy Richelieu, and Voltaire as a child, young man, and old narrator.