I think I don't get it ... solvemedia pays for the captchas solved if you use it on your site? That's great if it is so.
Yeah, sometimes instead of a captcha, solvemedia displays an ad with words on it. Advertisers pay to have their ad shown, and solvemedia gives some of that revenue to you. I don't think solvemedia isn't as safe as recaptcha though, so you might want to rotate your captchas.