Maybe I'm missing something here, but it doesn't seem like it actually runs anything, it just has you provide "commands" and "responses", so you have to fake out your entire interaction. Which means that when you change something in your program's input or output, you'll need to manually edit the script, instead of being able to regenerate it.
I think the point it's not to run anything. It's just a pure HTML/CSS/JS way of providing an example of how a CLI might work on a landing page. You don't need to record or make the user load a gif/mp4.
This was my thought exactly. Also thought seeing 6 lines being typed was too much, got the feeling I wanted to close the page. Animation went too slow and didnt really add anything anymore at that point. The power of gif-based samples is for the range 1-3 sec gifs I'd say.
Most of the time that a demo is done where the presenter is typing, it feels like I'm better served by the result of the code itself than watching someone stand quietly, type, and frantically hit backspace to fix the errors. If the actual code is relevant, why not have the block above or below the demo to review it line by line?