This is a fascinating deep dive into actors' portrayals of famous people like Johnny Cash, Ray Charles, Muhammed Ali, Julia Child, Bob Dylan.
From YouTube description: "Dialect coach Erik Singer takes a look at idiolects, better known as the specific way one individual speaks. To best break down this concept, Erik analyzes some actors playing real people. Just how close was Jamie Foxx's Ray Charles? What about Cate Blanchett's portrayal of Bob Dylan? Is Daniel Day-Lewis' Lincoln accurate?"