Don't understand your comment. It sounds very easy:
1) Buy or get a list of the one million most common pass phrases and passwords.
2) Generate the one million private keys by doing PrivateKey = SHA(password)
3) Generate the one million Bitcoin addresses from the one million private keys
4) Set up to sweep all coins sent to any of these one million Bitcoin addresses into your personal wallet
5) Wait for some sucker to use one of those password/phrases and profit!
Or better yet do this with two million password/phrases.
Sure it would take a few hours to do but "almost impossible"?
I guess he meant that anyone who would buy such a list is not tech-savvy enough to do step 2... that would involve some very simple coding at least.