Showtime's "In the 20th Century" is a millennium-related strand of feature-length documentaries in which famous directors take on major subjects of their choosing. In the fifth of the six films, "Funny Is Money," filmmaker Norman Jewison delves into the topic of comedy, using the hype surrounding the finale of the wildly successful NBC series "Seinfeld" as his launchpad to explore how the artform has evolved over the past 100 years.