This is a little concerning to see details of how to execute sniffing of FON username/passwords. I imagine that as a Bill it would be dangerous to lose this information because it would probably be possible to take your money from the shared revenue.
Other than that, while it's never good to lose a username/password I'm not sure if it's such a big deal.
The site recommends that you submit your captured file to them for decoding. The slight problem there is that now THIS site becomes a way to "sniff" usernames passwords: people test this using their own account, submit it to this site, and now this site has their logind details. Great idea.