when was the episode that is mentioned at the start first broadcasted?
May 15, 2012
Props (Glee)
Written and directed by Ian Brennan, the episode is the first of two new episodes that aired back-to-back on Fox in the United States on May 15, 2012. 
what episode of glee do they switch characters "Props" is it a musical film or series? It is the twentieth episode of the third season of the American musical television series "Glee". what is the plot in this above mentioned series? It centers on the fictional William McKinley High School glee club, the New Directions, which competes on the show choir competition circuit while its disparate members deal with social issues, especially regarding sexuality, race, relationships, and teamwork. who is the writer? Ryan Murphy, Brad Falchuk, and Ian Brennan who is the second mentioned person? He is an American television writer, director, and producer. what are some of his other notable series/films that he produced? "Pose", "American Horror Story", and "Scream Queens". what are some of the featured music in the episode that is mentioned in the beginning? Songs of many singers like Billy Joel's song, and original songs - "Loser like Me" and "Get It Right". was the episode criticized? UNANSWERABLE who is the first person mentioned above in the previous answer? He is an American musician, singer-songwriter, and composer. how did he start his career? He was a part of  two short-lived bands, The Hassles and Attila. what instrument did he play? Piano was he nicknamed after it? No, he was nicknamed the "Piano Man" after his first major hit and signature song of the same name.
wiki:7913807
Props (Glee) [SEP] Introduction
"Props" is the twentieth episode of the third season of the American musical television series "Glee", and the sixty-fourth overall. Written and directed by Ian Brennan, the episode is the first of two new episodes that aired back-to-back on Fox in the United States on May 15, 2012. It features New Directions preparing a new performance routine for the impending Nationals competition, an extended sequence in which Tina (Jenna Ushkowitz) has a vision of the glee club having swapped roles, including herself as Rachel, and an appearance by special guest star Whoopi Goldberg as NYADA dean Carmen Tibideaux. The episode received mostly positive reviews overall, though reaction to the musical performances was not as strong.