An "improvement" has been made by developers of spam and malware. Security research done in the Websense Security labs by Elad Shraf show that social engineering tricks are in the offering of free videos and vouchers. For reaching and seeing these special offers you have to install a browser plugin, they claim that this plugin is needed, but in fact it is malicious browser extension that becomes the tool for spreading the scam from one user's profile to another. Be aware of these "special offers" as they could be tricks to spread scams. These add-ons exist for Firefox and Chrome.