This question is really simple yet I can't figure out how to do it. What I'm trying to do is have the glitchify plugin/effect which is on a video layer, by itself on a black solid. Just the effect but not the actual video/layer. It sounds complicated but I just want the effect to show but not the background video footage on the same layer. I've tried all blending modes and keying the effect out doesn't look good either. Here's a screenshot of my project.
If you make three copies of the layer, one without the effect and two with, you can blend the first two in difference mode and precomp the result. On that comp you get full black where there is no difference between the two layers. You can use threshold to pull out all the areas that have been effected and use the result as a track matte for the third layer with the effect on it.