"I tried this service out and they have *horrible* payout. Around 10 to 20 cents CPM. Except the CPM they refer to is not the amount of captchas served but the amount of captchas solved.
So basically, if you annoy the crap out of 1000 of your visitors with these things, they'll give you, the webmaster, 15 cents on average.
Thats freaking horrible. Normal ad banners have CPMs near that and they dont require visitors to watch a video and type in text."
I am currently using it and experience the same *horrible* payout. When I questioned it I was told that the people typing in the responses where from outside the U.S. and currently they only had advertisers that were targeting U.S. citizens.
Also the payout threshold is a whopping 200 dollars. I am doing the math on what I make and that will take me about three years to reach.
I am still using it with the hopes that things will improve, but looking at my stats over the last thirty days it looks like this.
662 Solved TYPE-INs
That's a fair amount of solved Type Ins and so very little in revenue. And remember that is thirty days of revenue. I make more on two or three adsense clicks. I hope it improves so I am give them a glowing review.
There's also a short but recent thread on a web developer Q&A site with a compilation of thoughts on usability and revenue potential of CAPTCHA ads as well as how they defeat their own purpose by creating an additional incentive for spammers.