I watched/listened to these as I painted the bathroom last week. I recommend them.
Theology in Song
Keith Getty, Don Carson and Matt Boswell discuss the significance of theology in worship music.
Truth We Believe and Songs We Sing from The Gospel Coalition on Vimeo.
History of Hymnody
Audio of Kevin Twit’s course in the History of Hymnody at Covenant Theological Seminary is available free. (You’ll need to sign up for an account to download the lectures, but you can listen online without an account.) The course is described as “an investigation of the rich heritage of hymnody and its use in worship, including both classic and modern texts and music.” HT: Persis.