Thanks snojones, differences in translation would help explain a lot.

I played around with it for a while and figured out that I was doing some of the challenges wrong. I'm referring to the ones where there is a grid of different pictures rather than just one subdivided picture. When you click on one small picture, it disappears. Then, a few seconds later, another picture pops up in that square. I thought it was something like playing whack-a-mole so that the goal was to hit the "verify" button as quickly as possible after making all the (for instance) fire hydrants disappear, and before others have a chance to reappear. Unfortunately, that just results in another new challenge window altogether. One instead needs to keep clicking on all the reappearing pictures until Captcha stops replacing them.... then hit "verify". Not sure if that should have been obvious or not.

In any case, I still don't know how to determine if I'm a witch ;)

Nicolai