Will Smith turned in one of last year's most criminally overlooked roles with his turn in the fact-based drama "Concussion." Starring as the real-life Dr. Bennet Omalu, Smith believably brought to the screen the trials and tribulations of the forward-thinking doctor, the first person in the medical community to draw some very strong lines between football and the debilitating disease CTE. But just how good was Smith's performance in comparison to the real Dr. Omalu? 

Turns out, pretty good! As Omalu confesses in our exclusive featurette, at times it was hard for even him to tell the difference between photos of himself and of Smith once he slipped into character. Smith, for his part, also amusingly illuminates some of the decisions he made when it came time to imitate Omalu's distinct Nigerian-American accent. Take a look up above.

READ MORE: Review: 'Concussion' Starring Will Smith Struggles To Maintain Lasting Resonance

"Concussion" was released digitally today and will hit Blu-ray and DVD on March 29. It is the first new release to hit home video as a Sony 4K Ultra HD (previous titles re-released as Sony 4K Ultra HD include "The Amazing Spider-Man 2" and "Pineapple Express").