Turns out that Google has been selling banking trojans through ads on YouTube:
http://labs.bromium.com/2014/02/21/the-wild-wild-web-youtube-ads-serving-malware/
Google has sold the functionality to a Dutch malware company front, and people that have watched YouTube videos on a Windows machine and that have been presented with that ad, should check their systems. It's a tough trojan to detect on Windows software, so it would be wise to use ClamAV, but on the other hand, the virus should not work any more if java is properly updated on the system.
People that use other operating systems are not affected, nor people that use adblock or noscript or the likes.