There has been a sudden outrage of SPAM on Facebook, with spam bots posting videos and links on your wall. Here’s a quick tip to keep the garbage away:
Go to: Account >Privacy Settings > Click Custom > Customize Settings > Under the column “Things Others Share” Uncheck the checkbox under “Friends can post on my Wall”
Anything important, people can still send you a private message instead of posting on your wall.
I hope this helps.