Someone with more experience in video editing will have to help with the specifics, and also it would be very helpful for us if you told us what editor you are using.
Basically what I would do is add a blur of sorts to blur out the edges of the film. Then I would cut out small parts of the film. Say Person (Jim) is at point A and then walks to point B. I would cut out some (Not all! he isn't teleporting) of the walking and then put him at point B and make it slower so it would show him sort of walking and then jolting forward like the flashback was incomplete. There are also effects to add ghost trails behind the object, which would leave a low opacity trail of the object behind him as he's walking, which shows the flashback as being incomplete and blurry.
thanks again! 
Liked it.