With: https://www.ffmpeg.org/ (brew install ffmpeg)
The command I used to strip the unused/silent audio channel + "hint for streaming" was:
ffmpeg -i my-video.mp4 -c copy -an -movflags faststart my-video-nosound-hint.mp4
This caused an 8MB video which was too big for web usage, to become a 10MB file that plays immediately while the video is still downloading.
- Before: Lighthouse complained about the page and the video file (Rightly so).