Today, members of the Internet communities 4chan and and other enterprising computer whizzes hacked YouTube using a vulnerability in the site’s comment system. While the hack was used on a variety of videos, striking music videos featuring teen pop idol Justin Bieber was the most popular activity. Twitter lit up with complaints about the problem, Google support got some concerned posts on its forum, and we received tips in our inbox. The event caused quite a Sunday-morning stir. The bug allowed users to inject HTML (the code that most websites are built with) that could be executed on the site, whereas HTML within comments is supposed to be restricted. The hackers did everything from force pop-up messages to appear over the site declaring that it had been hacked to redirecting Bieber video pages to sites hosting pornography and malware. http://mashable.com/2010/07/04/youtube-hacked/
I hate how people always link shit like this to 4Chan. Honestly, /b/ are nothing like what they used to be and they have no organization at all. This was obviously a couple of people who might be affiliated with 4Chan but I can't see /b/ actually organizing this.