My $0.02 would go towards buying the "s" at the end of lyrics. In casual usage I would almost always say "I can never understand the lyrics to that song," but I think deep down I know that the singular is the "correct" form.

Note that you (well, I, anyway) would never question that the singular "melody" is appropriate when referring to the collection of notes that make up a song , but most of us want to make the words plural.