I used a site recommended by Chris Anthony a while ago:
http://www.tools4noobs.com/online_tools/youtube_xhtml/
You plug in the Youtube URL, click the button that says "Generate code", and it automagiically creates a code snippet that you can cut and paste into your message here.
If you want to clean it up a bit, just copy everything starting with the opening "object" tag and ending with the the "/object" tag - anything past that tag is not really needed. |