You tube videos can be displayed within your post on the forum.
On a New Thread form or the "Full Editor" reply form, click on the video icon.
Choose You Tube Video from the menu.
Copy the you tube address for the video and paste just the identifier code for that video into the Youtube box on the pop up form.
In this example, paste just: 1hVFccikIIk
Not the full URL address: https://youtu.be/1hVFccikIIk
It may not show in the preview, but it should display within your post when you submit it. Click on "Contact" at the top of this page if you have trouble.