As you've noticed, ning supports the posting of embedded videos right in the body of your post. How to do it, you may ask? (Well - actually, ubu did ask.)
OK, let's say somebody starts a discussion titled "Songs About Laundromats." Right away, of course, you think of the song "Laundromat" by Rory Gallagher, but somebody else (let's call her Julie) has already posted that. So you go with Plan B - "Leader of the Laundromat" by the Detergents - and decide to get fancy by embedding the video itself.
After pulling up the YouTube page with the song "Leader of the Laundromat" (featuring lead vocals by Ron Dante, who also sang lead on the Archies' "Sugar Sugar," a gratuitous piece of information wholly irrelevant to the current topic - but hey), you look in the upper right area of the screen. There you'll see a text box with the word "Embed" to the left of it. Single-click the cursor in that box once and it will select the entire contents. Then right-click in the box, select "copy," then paste it into the body of your post. (Except you'll find that, in the meantime, some clown with the initials JD has already beaten you to it, requiring a fallback to Plan C - "The Blues Are Still Blue," by Belle and Sebastian.)
Yep, ultimately we're at the mercy of the vagaries of YT - including the dreaded "Embedding disabled by request" message you'll occasionally find in the Embed text box, as illustrated by the following (laundry-related) video from (my personal guilty pleasure) Amy Grant.