The Blair Witch Project (1999)
(Synopsis provided by IMDb.com):
Three film students vanish after traveling into a Maryland forest to film a documentary on the local Blair Witch legend, leaving only their footage behind.
The Blair Witch Project was another game changing found footage film that caused controversy at the time of its release. Before its debut, the people behind The Blair Witch Project created a clever marketing ploy that included missing posters of the three actors. This truly made audiences believe the actors were really MIA and the movie was real found footage.
Not a huge fan of found footage but my favorites include Wekufe: Origin of Evil and Be My Cat.
Ohhh yeah I remember you reviewing both of those.