This is a pretty good video
However I am disappointed in his explanation he gives of the read head. Read heads haven't consisted of coils of wire for some time as they suffer from issues such as a low signal to noise ratio and different response magnitudes depending on where the head is radially on the disk. Most hard drives now use some form of spin valve which does not rely on Faradays law of induction.
(, Thu 9 Jun 2011, 23:26, Reply)
Then again he did say it consisted of a coil of wire "at its simplest" so I'll let him off.
(, Thu 9 Jun 2011, 23:27, Reply)