This video was all over the internet, at the same time that it was widely reported that an abandoned annex of the U.S. Embassy in Tripoli was taken over by a group of armed rebels. According to the Washington Times, those in the video are members of an Islamist militia group called the Dawn of Libya:
A commander for the umbrella Islamist militia group, the Dawn of Libya, told The Associated Press that his fighters had been in control of the compound since last week. The group granted access to the compound to an AP reporter, who said some windows had been broken, but most of the equipment there appeared to remain untouched.
The news was that the residential compound was seized, but the main embassy structure itself remains undisturbed. The U.S. government withdrew all employees from Tripoli weeks ago when violence and unrest increased between rival groups.