To show a youtube video in one of your posts, just make a new row, change it to video, click the youtube link and paste the youtube url into the text field.
Yeah, that's what I did. I posted the title, then the link: Frank's 2000" TV [MEDIA=youtube]ugq9Sa2L6GQ[/MEDIA]
Ah this post was made before the posts went JSON.
Now you need to make a row, change it to video, then use the youtube field to paste the url into.
Then click ADD and you should see the video appear.
Then save your post.