Maybe you can adapt this code snippet for that purpose.
Code:
frame = 1
last = movie.FrameCount()
video = AutoCrop(movie.trim(0,0),0,716,424,0,0,0,0,30,1,0,0,0)
GScript("""
while (frame < last ) {
video = video ++ AutoCrop(movie.trim(frame,frame),0,716,424,0,0,0,0,30,1,frame,frame,0)
frame = frame + 1
}
""")