Okidoki, I understand now what you don't understand.
Indeed YOOtheme is quite powerful and it has Elements for many things, including video, images, galleries etc.
Let's take the example of Advanced Custom Fields by Tassos which has a field "YouTube" and another one "Vimeo", with *plenty* of options.
Well when using YOOtheme builder, if you choose any Element it will fetch the *rawvalue* of that Custom Field. It is not possible to have the "normal rendering" of a Custom Field.
So in practice I cannot use ACF YouTube and ACF Vimeo with all their options set in the Custom Fields... except precisely if I use "Events before display" or "Events after display" bc there it will call all my Custom Fields with Joomla's original rendering.
Am I a bit clearer?