TinyMCE: Configure iframe sandboxing to allow YouTube domains

In TinyMCE 6.8.1 (the WYSIWYG editor used by Bludit) iframe sandboxing was introduced. This automatically adds the sandbox="" parameter to all inserted <iframe> -tags. This blocks all embedded videos from playing, even when the CSP-Headers are correct. As I just wanted to write a short blogpost about a YouTube video which discusses why we Germans are able to eat raw pork (" Mett ") and suddenly…