There is a new phishing attack doing the rounds on Facebook. You will be able to recognize it because it is labeled as "The is without a doubt the most hilarious Facebook video ever LOL". There is also a picture of a woman in a short skirt. So be careful and do not click on it. If off course you are tempted and would like to click on it you are redirected to a phishing site. The page you are taken to is a page that looks like the original Facebook sign in page. This is no Facebook page as you will be able to notice from the address bar. If you do sign in you are then redirected to an application that wants to access all your information. In addition a malware program is installed on your PC.
The Facebook application is often called "Media Player HD". So if you fell for this attack change your Facebook password. Delete this application and run a virus / malware scan on your computer.
This video from websense explains it further.