Sometimes, threats of “Pay money or all your files are gone forever” are not convincing enough. Maybe the victim has everything backed up in the cloud, or maybe there was nothing on the computer but cat photos. To really drive the threat home, ransomware developers have gotten very good at, ah, marketing.
The purpose of any marketing is to represent a product in such a way that the consumer will be compelled to part with their money. One way is to show a fake message from the FBI accusing the victim of viewing child porn.
This one threatens to send a copy of all your skype conversations to your contact list (no one has reported that this actually happened. Hackers are unlikely to act upon this threat, because large file uploads increate the risk of getting caught.)