Another theory on the ending
I read a lot of theories about the ending, and I see that most people's problem with the ending is that he disappears, while the camera is not, and it gets duplicated.
Now what if it _wasn't_ the destroying of the time machine that caused him to flicker and fade out from reality?
In the movie we have seen exactly one type of event that causes this: someone having an eye contact with himself.
In the old video, David in the mirror isn't injured. In the end he's bleeding.
So what if the uninjured David and bloody David are two separate instances, and they met, annihilating each other from existence?
Can this explanation work?