At the beginning of your Blair Witch adventure, you will find a video camera. It's not just a device used for recording events, it also allows you to manipulate the surrounding reality. The following page of the game guide will tell you how to use the video camera
While playing chapter 3, you will come across a video camera. From now on, it will become an integral part of the gameplay. The device will allow you to see in the dark, which would not be possible with your basic flashlight. This allows for the so-called night mode. It works well in situations in which there is complete darkness, and you are in an open area with no trees (chapter 6 for instance). Your flashlight wouldn't be able to illuminate what's right in front of you.
The second important feature of your video camera is the ability to manipulate reality. During the gameplay you will come across a lot of videotapes that reveal the story of the missing boy. However, this is not their only function. They also allow you to manipulate the reality around you. If you stop the video at the right time, objects that will let you proceed with the storyline will appear in the game world.