What Does The Ending Of Blair Witch Really Mean?
The Witch's Time Travel
An essential, newly introduced skill of the Witch is her ability to manipulate time. We first see this when everyone oddly sleeps in until 2pm, and is hammered home when Lane and Talia turn up after being lost for "six days", compared to the group's one, and Lisa's 7am alarm wakes her and James in the middle of the night. At the end, this is pushed to the extreme, with the Witch rushing through days in matter of seconds.
This particular power explains how the Witch is able to so easily ensnare victims, confusing and trapping them before having to physically alter the woods.
The big reveal, however, is that the film that inspired James to start off this whole journey is actually the one we're watching - it was shot by Lisa as she was running through the house, meaning we're dealing with an infinite closed loop; the Witch released the tape weeks in the past so she could ensure the gang would come to the woods.
While at first this may seem to be a new trick - the Witch can also go backwards in time - logically it's an extension of the time dilation, just on a much larger scale. Aside from allowing for a down-played twist and the snazzy lightening effect, however, this leads to a lot of big reveals about the other characters.