YouTube embeds are not scaling proportionally

I really like this theme and I’ve been making some decent modifications to it. But I cannot figure out how to get the YouTube or well any video embeds to scale proportionally. I can use a plugin, but that causes some weird problems so I would rather try to fix it with CSS. But I need some help.

Here is the responsive CSS for the videos that the creator wrote:

embed,
iframe,
object,
video {
	max-width: 100%;
}

Here is a link to a post on my website that has a video if it helps any. https://nickerwin.com/2015/02/why-im-not-shooting-fireworks-this-july-4th/

Thanks in advance!