Hi!
Video embed box is very small and cannot be expanded.
It also doesn’t scroll line by line, but skips lines.
In practice, if user wants to add/remove something in the embed code (this is often the case, like various parameters), then some lines cannot be reached due to line skipping on scroll.
I rarely use embeds but I think that in general UX of this part can be improved by making the box bigger or expandable.
Thanks!