TCM’s Mad About Musicals celebration continues today and tonight, with musicals shown all day and throughout prime time. Best of the bunch: At 8 p.m. ET, James Cagney playing a patriotic show-business firecracker, portraying showman and songwriter George M. Cohan in Yankee Doodle Dandy. The ultra-patriotic movie was released in 1942, the year after the USA entered WWII.