Also another way
To post a YouTube.
1.Note the YouTube URL for the video
for example, the one below
http://www.youtube.com/watch?v=F37VQnMhssg
2. Copy after the = symbol, the code letters and numbers
for example from the one above
F37VQnMhssg
3. Click on the YouTube icon in the post toolbar
and you will see [extendedmedia]https://www.youtube.com/watch?v= {/YT] appear.
4. Post that code in between, and Hey Presto!!