Here is recent post that Tim Keller wrote with regard to Martyn Lloyd-Jones' statements about the primacy of preaching. In the course of the post, Keller mentions the Doctor's warnings about the use of recorded sermons. I remember hearing Lloyd-Jones' strong warnings against the use of audio recordings, while listening (the irony of it all) to his Preachers and Preaching lectures in seminary. I didn't fully grasp, then, what he concerned about; having seen all the anti-ecclesiastical abuse over the years, I better understand the caution. Keller writes:

Dr. Lloyd-Jones effectively dismantles the idea that watching a video or listening to an audio of a sermon is as good as coming physically into an assembly and listening to a sermon with a body of people. It is obviously a good thing if a person who never hears or reads the Bible listens to the recording of a good gospel message and is helped by it. But the Doctor argues that people experience the sermon in a radically different way if they hear it together with a body of listeners and if they see the preacher. Watching on a screen or listening as you walk detaches you and the sermon becomes mere information, not a whole experience. There is a power and impact that the media cannot convey.