Hello,
Thanks for reaching out.
If you want to display YouTube videos in the frontend when using WYSIWYG field, you need to use the embed code from YouTube, like
<iframe width="560" height="315" src="https://www.youtube.com/embed/0Tch0N5nsRU?si=asOF9uYrSx8gOD2X" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
and set the sanitize callback option to none to save the HTML tags. Following the documentation https://docs.metabox.io/sanitization/