Feature-Request: Responsive Video Embed

I know Kirby CMS is a lightweight CMS and I don't want to change that key feature!

But I think it would be nice, with RWD in mind, to add an responsive embed option to video embeds (especially Youtube and Vimeo).

So I thought https://github.com/davatron5000/FitVids.js would fill the gap quite nicely and it would be a nice option to include when a responsive embed is necessary. But maybe there are some other lightweight methods to enable responsive video embeds with iframes etc.

But I just want to start working on that because I think it would be a nice option for not-so-techie users.

What do you think about it :question: