movipy NeedDownloadError缺少插件ffmped解决方法

File "/Users/macbook/python/main_video.py", line 3, in <module>
        from moviepy.editor import VideoFileClip
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/moviepy/editor.py", line 22, in <module>
        from .video.io.VideoFileClip import VideoFileClip
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/moviepy/video/io/VideoFileClip.py", line 3, in <module>
        from moviepy.video.VideoClip import VideoClip
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/moviepy/video/VideoClip.py", line 20, in <module>
        from .io.ffmpeg_writer import ffmpeg_write_image, ffmpeg_write_video
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/moviepy/video/io/ffmpeg_writer.py", line 19, in <module>
        from moviepy.config import get_setting
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/moviepy/config.py", line 38, in <module>
        FFMPEG_BINARY = get_exe()
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 86, in get_exe
        raise NeedDownloadError('Need ffmpeg exe. '
    imageio.core.fetching.NeedDownloadError: Need ffmpeg exe. You can download it by calling:
      imageio.plugins.ffmpeg.download()