Well, this is exciting. Trinity Evangelical Divinity School has released 4 video lectures by D. A. Carson on the book of Hebrews. I’ve only made it through the first and have greatly benefited.
If you’re not aware already, you should know about Biblicaltraining.org. They have scores of free seminary level courses in Old Testament, New Testament, systematic theology, Church history, Apologetics, Pastoral theology, and much more. You need to register in order to listen to the lectures, but there’s no charge whatsoever.
Here’s are my favorites by Christian philosopher and apologist Ronald Nash: