If you use the YOUTUBE option feature in the compose message screen, then the video will play inside of your post.

If you go here in the HELP & FAQ forum  http://civilizeddiscussion.boardhost.com/viewforum.php?id=11 you'll see complete directions on how to post pix, links, and youtube videos.  There are dozens of other "lessons" on how to use these forum boards to their best advantage.

The directions for youtube posting:

Posting LINKS - PICTURES - YOUTUBE VIDEOS

I've discovered that it is easiest and better results when you use the ATTACH IMAGE and ATTACH LINK functions to add pictures or links.  The automatic functions use the correct BBC instead of having to use trial and error.  Remember, this forum uses BBC more so than HTML.

POP UP BOXES will come up to the right of the post where you can paste the links to images, youtube, or webpage you want to share.  If you don't use the pop up, then your links, pix, and youtube videos may not display properly.