Nothing really to add to Child & Fordim's posts, except that there was a video out a few years back:
http://www.amazon.co.uk/exec/obidos/...551119-6814227
Unfortunately its not generally available, but I think you can still get it from the Tolkien Society.
There are some long interviews with Christopher, John & Priscilla Tolkien, as well as Shippey & Flieger. Part of the interview with Christopher goes into this issue of the machine, & Tolkien's understanding of it, & his distinction between the man made & the machine.