The people who caption the episode must have taken pity on the poor viewer who was hoping for a lighter ending to an old-fashioned Monster of the Week episode. Their parting interpretation of the lyrics: It was a new dayesterday, butt's an old D now. Butt's an old D now, indeed, my friends. I hope you've learned that much, at least. D, huh? I wonder if that's a secret message from Cas.
Next week looks black and white and blue all over, as the Winchesters encounter some class movie monsters. It'll take them 30 years to catch up with that Montgomery kid. They've got to keep busy, somehow.
Demian is the Supernatural Recapper, and he's generally accompanied by his faithful, if imaginary, gay dragon companion, Raoul. Cindy McLennan is just the substitute. She and Raoul got off to a rough start, so she mostly goes it alone, or tries to anyhow. You can e-mail her at CynthiaMcLennan[at]gmail.com.