The Trix editor is, in a word, 'basic'. It's also extensible, which comes in very handy when you want to do things like add code samples and Vimeo videos.
Spina gives you a generator that lets you add embeddable content as you need. It comes with the most common, including YouTube, Vimeo, and a Button. You might want to do something more complex, like adding a GitHub gist, which is what we cover in this video.
You can get started with:
rails g spina:embed gist url
This creates a model, a form, and your HTML output.