The video documentary below is about a number of accounts of people that have been tormented by upset ghosts. Normally ghosts cause no threats to humans and will not be noticed much.. However occasionally this can be different. This is what I refer to commonly as emotional ghosts or upset ghosts. They can throw things around and even try to hurt occupants in an occupied house (haunted house).
These types of ghosts are commonly referred to as poltergeists and by many religious organisations as demons. How they get this way has many theories, one being they were victims in life and so even in death they are after resolution still.
Another theory is confusion that they are dead, often referred to as a nirvana a state between worlds where the ghost still thinks they are alive physically and so is upset people are in their home.. In this state some believe rationale is not possible as that is a element of the mind so the ghost forms into a confusing pattern.
Real Ghosts Caught on Camera
(The ghosts caught in this documentary film above have been studied and confirmed for authenticity. The ending of the second part however is completely for shock value only..)