Not the most elegant way to achieve this, but it does the job, remember to alter the frame setting in the blankclip command for the length of video you're comparing, as well as the width/height/fps if you're working with NTSC:blankclip(length=2981,width=720,height=576,fps=25,color=$000000)clip1=avisource("before.avi").crop(0,0,360,576)clip2=avisource("after.avi").crop(360,0,360,576)overlay(clip1,mode="blend",opacity=1)overlay(clip2,360,0,mode="blend",opacity=1) Report