Only works on videos recorded after download – Video Zoom! - Apply Zoom, Crop Review

I was hoping this could be used to edit video that I had in my photo/video library. Unfortunately it seems to only work on videos that are recorded after you have downloaded the app. Don't understand why that would be. Too bad- the app seems pretty cool when it does work.
Review by Disappointed RPI fan on Video Zoom! - Apply Zoom, Crop.