Use of brainpower (updated)

Here's a neat trick - getting people to work for you by using what they're doing anyway to do another job simultaneously:

It happens all the time: you're registering a free e-mail account or making a purchase online, when up pops a wavy, multicolored word. The system asks you to retype the word - and you roll your eyes, squint a little, and transcribe. This little test is one of the most successful techniques for making sure the person trying to log on is really a human, and not a digital "bot" prying into the site.

But now, when you type that word, something else may be happening as well: You may be deciphering a word from a decaying old book, helping to transform a historic text into a new digital file.

For further explanation, follow the link. But should the beneficiaries of this process be paying the unsuspecting decipherers for their efforts?

Update on August 19. A vigilant reader with something I failed to spot:

There's a logical flaw in your argument (or rather, in that of the article you quote). Suppose you are prompted to re-type in a word covered with a wavy line as an authentication that you are a human being. Then, the system doing the authenticating needs to already know the correct interpretation of that word - ie, before you type it in. You cannot be the first person to interpret the word correctly, because if you were, then that word could not be used for authenticating you. So this statement you quote is clearly false: 'But now, when you type that word, something else may be happening as well: You may be deciphering a word from a decaying old book, helping to transform a historic text into a new digital file.'

(Thanks: PMc.)