Own work

This file is easily generated using Python with the following libraries: numpy, gizeh, moviepy:

import os
import numpy as np
import gizeh as gz
import moviepy.editor as mpy
figpath = '../figures'
W, H = 1000, 600
r = -W/64
duration = 3.
start = duration*.2
stop = duration*.8
duration_flash = .05
fps = 50
flash = gz.rectangle(lx=r, ly=r, xy=(W/2., H/2.-r), fill=(0,1,0))
def make_frame(t):
    surface = gz.Surface(W, H, bg_color=(0, 0, 0))
    if np.abs(t-duration/2) < duration_flash: flash.draw(surface)
    if start < t < stop:
        rect = gz.rectangle(lx=r, ly=r, xy=(W*t/duration, H/2.+r), fill=(1,0,0))
        rect.draw(surface)
    return surface.get_npimage()
clip = mpy.VideoClip(make_frame, duration=duration)
clip.write_videofile(os.path.join(figpath, 'flash_lag.mp4'), fps=fps)