What model? It got right first try here with your exact prompt using the free GPT-4.1 model.

https://i.imgur.com/toLzwCk.png

ffmpeg -i movie.mov -c:v libx264 -preset medium -crf 23 -c:a aac -b:a 128k movie.mp4

BUT, I have this in my copilot-instructions.md file:

    # Always follow these steps when responding to any request
    1. Please do a round of thinking in <thinking></thinking> tags
    2. Then a round of self-critique in <critique></critique> tags
    3. Then a final round of <thinking>, before responding.
    4. If you need more information, ask for it.