You'll see a new Youtube button on the toolbar. It lets you embed a video right into the post itself.

This is how it works:

You go to a youtube video, for example, http://youtube.com/watch?v=j96uqRKzHDI
and then copy that code at the end, after the "v=".

Then click on the youtube button in the toolbar and paste in that code.

Then you get:



Cool?.

This only works for Youtube videos, by the way.