I Am Not a Rock Star: A fascinating musical journey, from intro to finale RICK GROEN The Globe and Mail Last updated Friday, Nov. 16 2012, 12:50 PM EST What becomes a documentary most? Time, perhaps, the luxury to study and shoot the subject over a period long enough to transform your film from a snapshot to a moving picture. In the case of I Am Not a Rock Star , that luxury is a necessity, since the focus here -- like Michael Apted's 7 Up series or Nikita Mikhalkov's Anna -- is on the growth and development of a child. Like all children, this girl is unique. Unlike most, she's also uniquely gifted: Marika Bournaki is a piano prodigy. Director Bobbi Jo Hart's camera tracks her through the entirety of teenagedom's turbulent course, from 12 all the way to 20. Yes, classical music abounds -- Schumann, Rachmaninoff, Bach -- and it's an aural delight. No doubt, better educated ears than mine will appreciate the maturing of Marika's technique, her evolution from prodigy to professional, raw talent acquiring its hard-earned polish. But that is not really Hart's purpose here. Instead, she sets herself a much more sensitive task -- weaving the special circumstances of this particular teenage into the common fabric of every teenager. It proves to be fascinating exercise, with stops at approximately two-year intervals. First, then, the self-assured 12-year-old: Marika, in her native Montreal, switching effortlessly from French to English and back again; Marika, in New York, already