Code:
X=480
blankclip(width=960,height=1080,length=X)
stackhorizontal(last,last.invert,last)
animate(last,0,X-1,"crop",0,0,1920,0,960,0,1920,0)
mask=(last+last.reverse).loop(100)
a=colorbars(width=1920,height=1080)
b=version.pointresize(1920,1080)
overlay(a,b,mask=mask)