The code work well.

However, after configuring ffmep, the first time I ran the code I got this error:

RuntimeWarning: Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work warn("Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work", RuntimeWarning)

To solve this error, I install ffmpeg package with the pip then log off OR restart windows.