Like this.
Watch the video on Youtube and go to the address bar near the top of the page. Click on the address and, holding the left button on your mouse down, drag across the address to highlight it. Right click and select copy from the drop down menu, then come here, start a post. Right click in your post then choose paste from the drop down menu. Type your message, then submit it. Presto chango, there it is. It should look like below, but with the http://. I took out the http:// so it wouldn't post the video again!
Damn, even with the http:// out, it posted the video again!