Dopplegangers and Video Cameras
I watched Cloverfield and Pontypool before this and my girlfriend told my Rec is also a sort of 'realistically' shot movie ala Blair Witch.
It might seem strange I put Pontypool here, but it also had the same feeling of the others. Though it wasn't done with video camera shots, it inspired a level of claustrophobia and realism. I felt while watching it as if I were another person trapped in the radio station.
Lake Mungo is again slightly different, shot like a documentary. But these movies all evoke a sense of realism due to their effort to appear 'low budget' i.e. all images and sounds seem to like that 'crispness' you get in the image of regular films. This was originally, as far as I know, done in the first Blair Witch.
What I am curious about is all the films above, as well as Paranormal Activity and except Blair Witch, were done in the same few years. Cloverfield, Pontypool and Lake Mungo were all released in 2008. It seems a strange coincidence that several movies have latched onto similar ideas.
This movie over all was very cool. It wasn't scary, per se, but it did create a very unnerving atmosphere. And that image in the cellphone camera is literally burned into my brain. It was that freaky.
Also, it references a rather unusual type of ghost, the Doppelganger. A doppelganger is a ghostly double of a person which when it appears to the person's friends signifies their death and when it appears to themselves is an omen of death as it was in this movie. There have been several famous people who have claimed or had family members claim to see such beings. There's an article on wikipedia about it: http://en.wikipedia.org/wiki/Doppleganger