My understanding is that, for $3 the author creates a transaction from some wallet of N bitcoins under the author's control, that has a distribution of:

   0.000000001 to <hash of document>
   N - 0.0000000001 - <fee> to owner's wallet #2
   <fee> to miner

So the $3 doesn't buy you any bitcoins, since the address that is the hash of the document isn't a valid bitcoin address since it wasn't generated from a public/private key that is known.