1. Copy the url after the = sign
http://www.youtube.com/watch?v=
LxDYnu1S_Xs
2. open the reply box and go into advanced and click on the youtube icon
3. A box will appear in which you will type the subject of the video clip you are posting, it will be whatever you want to call it.
4. Then you will paste the partial url in between the brackets that appear after what you named your clip.
5. Hit preview post to see if it loaded right.