This solution is interesting, but it fails on two counts: 1. You're making the process even more of a pain in the ass, not less, increasing the likelihood that

This solution is interesting, but it fails on two counts: 1. You're making the process even more of a pain in the ass, not less, increasing the likelihood that real users will abandon the registration. 2. This doesn't protect at all from the human captcha-cracking farms.