This video is an advert for the London Dungeon made in 2006.
It starts off with the following text:
"The footage you are about to see is absolutely genuine and was captured by CCTV cameras at the The London Dungeon."
"Look very closely and you will see a mysterious ghostly figure. The video has been thoroughly analysed by experts but they have so far offered no explanation as to what it is."
In the next scene, there are two fuzzy separate security camera images with the words "MAIN EXT JACK ENT" on the left and "PRIS DR" on the right. The time stamp 05:59:50 and the date 20-11-04 are displayed at the bottom. The image goes fuzzy for a moment and the time advances to 10:09:43. You can also see, what appears to be, a janitor holding a broom walk out of range of the camera on the left.
After about 34 seconds into the video, a man, with long white hair, black teeth and wearing rags, jumps up, his face filling the screen, and yells "YEAAAH!". He stays like that for a while, staring at the camera with his mouth wide open. After a brief pause, he seems to faint, and descends into oblivion. The following text then reads "Did you spot it?"
NOTE: The following video contains a screamer.