A top country songwriter, Barry talks about writing hits for Little Big Town, Tim McGraw and Jason Aldean.
He wrote "She Blinded Me With Science" so he could direct a video about a home for deranged scientists.
In the name of song explanation, Al talks about scoring heroin for William Burroughs, and that's not even the most shocking story in this one.
Medley looks back on "Unchained Melody" and "You've Lost That Lovin' Feelin'" - his huge hits from the '60s that were later revived in movies.
Tom talks about the evolution of Cinderella's songs through their first three albums, and how he writes as a solo artist.
You know the scenes - Tom Cruise in his own pants-off dance off, Molly Ringwald celebrating her birthday - but do you remember what song is playing?
Celine Dion's 1998 festive tune "The Magic of Christmas Day (God Bless Us Everyone)" came from an unlikely source. It was penned by Dee Snider of the heavy metal band Twisted Sister.
The disco song "Good Tmes" by Chic was a huge influence on early rap, providing the bassline for "Rapper's Delight."
Ariana Grande's hit "Problem" started off as a track written by One Direction songwriter Savan Kotecha. He gave it the working title of "The Whisper Song," after a 2005 Ying Yang Twins hit.
Damon Albarn found inspiration for Blur's "Girls And Boys" whilst on holiday in Magaluf on the Spanish island of Majorca.
Ed Sheeran's first single was "The A Team," a song about a drug-addicted prostitute.
Ed Sheeran's "Bloodstream" was written after an experience taking MDMA during a wedding celebration in Ibiza, and it's basically about all the feelings that he got from that time.