Do you mean to have a card appear when someone adds a YouTube link in the text within Medium/Summernote/etc?
If so, you’d need to do this yourself manually. It wouldn’t be hard, just not built in to Trix.
Simple Trix implementation · GitHub I would recommend starting here, as it was the simplest template to begin with (if using Trix; you’ll need to set up bindings via DMX bind in code)
Although you my be correct, better safe than sorry - especially if allowing HTML input. Here’s my approach and here’s a comment from patrick re: sanitizing if helpful 