This is not exactly correct. I recently had to cut (for reasons) an mp4 video somebody sent me over Whatsapp. After fighting with ffmpeg for a day - they hey

This is not exactly correct. I recently had to cut (for reasons) an mp4 video somebody sent me over Whatsapp. After fighting with ffmpeg for a day - they hey word here is "keys" - because there were issues with the video: Sound would start at point but video didn't, or the first part before the first key in it of the video was re encoded and the quality was crap I finally resorted to using Handbrake, that did the job I needed. Just get any short video somebody sent you and try do use this script, and you'll see what I'm talking about.