I found this interesting clip on Youtube which seems to be an honest capture on CCTV.
Here is the poster`s explanation.
`Ghostly Orb in the Western Suburbs of Adelaide, South Australia. Really weird Ghost Sighting on Security Cameras.
A little bit of information about the hall...there is no windows and that footage is in night vision mode so the hall is technically black. Yes possibly could be a bird or bat, but unlikely as an animals movements would be a little more erratic.. Still not sure what it is though so still very weird..`