The synesthesia seemed to help him almost as a trigger for past experience. I think that some of these estimates fail to account for the visual image storage capacity of the brain. I have actually certain events in my life, in an animated fashion, not as a series of stills. A storage capacity of only 10 trillion would only render about 166 minutes of animated memory. I there is more than that in my own head.
Some folks theorize that the brain subconsciously records all events which occur in one's lifetime.
This is evidenced by the use of hypnosis to allow subjects to relive the past, even birth. I personally prefer the latter. Please excuse the large doses of ignorance in this message.