To create funny videos, I needed to switch the audio to a song or movie. I got help from 2 commands: youtube-dl and ffmpeg
youtube-dl --extract-audio --audio-format mp3 --output new_audio.mp3 "https://youtube.com/watch?v=<video id>"
ffmpeg -i my_video.mp4 -ss "2:06" -i new_audio.mp3 -c copy -map 0:v:0 -map 1:a:0 -shortest funny_video.mp4
I’ll give credits to: ffmpeg - replace audio in video to get me the ffmpeg arguments.