messages = ['Dog', 'Cat', 'Duck', 'Wolf']
clips = [mp.TextClip(txt, fontsize=170, color='green', size=(500, 300)).
    set_duration(1) for txt in messages]
concat_clip = mp.concatenate_videoclips(clips)
concat_clip.write_videofile('texts.mp4')
How to concatenate videos in moviepy?