Seems like Prezi has changed its mind about not paying. Prezi being a Hungarian startup made a buzz in the local media with this story and one of the leader news site reached out to them and got this reply: "Prezi: Hibáztunk és fizetni fogunk" witch means: "We made a mistake, we will pay"

They also said that they will release a blog post and they will change the bounty program, so mistakes like this will not happen again (hopefully)