Can someone explain this to me please? It seems as though it's touting itself as a CAPTCHA for site owners, but as an interactive ad block for advertisers? I c

Can someone explain this to me please? It seems as though it's touting itself as a CAPTCHA for site owners, but as an interactive ad block for advertisers? I can't really work out how this works on a site? Is the idea that I use this type of CAPTCHA for 'human' sign ups, and at the same time, an advertiser gets a hit? Almost as in, to sign up, you need to see this ad? Either way, it's interesting: I also like the secondary result of "you don't get free impressions". ie. you only pay if they click or 'solve', but at the same time, they can't see the ad, remember the name and look for it elsewhere without essentially triggering the payment if that makes sense.