How to stack frames of a video together using lighten blending mode? I want each frame of video to get added on top of the previous frames. I don't want any of them to fade out. I am shooting locked down with a black background. A model moves through the frame with a light. I want to stack the frames one on top of the others so that the light moves through the frame and the last frame shows the path taken as a light trail. 

What is the easiest way to add each new frame on top of the rest? I would like to avoid putting a separate layer for each frame manually.
Use "Echo" effect. I believe it will suite you.

You need adjust it. Make number of echos equal to your frame count.