The video appears to show a cruise missile hitting the west side of the Pentagon creating a small white puff of smoke.
I was on the roof of a building on the south side of the Pentagon at the time of the impact and there was a very large black cloud of smoke that wafted up into the sky. In addition to this small debris rained down from the sky for several hours afterward.
The video also appears to be taken from a pretty good height and changes the point of view slightly as it progresses almost appearing to be taken from a helicopter.
However there were no helicopters in the air at the time of the impact near the Pentagon. In addition, to this there are no tall buildings in this area (west of the pentagon) indicating that the video would have to have been taken from some type of aircraft (probably some old footage that was doctored).