The watermarked images indicate that they didn't pay for the images, and apparently the watermark doesn't bother them. However, as a thinking person (minority, these days), I wouldn't attend whatever function or buy whatever they're selling because if they'll steal from the stock site and the photographer, they'll do that or worse to you and me. Displaying stolen images like that only serves to broadcast their lack of character and integrity, and their stupidity. So since they're not likely to accomplish anything significant and become a major player, buying lots of images, I think it would be a waste of valuable time and resources to pursue any kind of action against them. On the other hand, the owners of the images might be doing the culprit a favor by teaching him that theft is wrong and choices carry consequences (or benefits). Too many people don't understand that these days.