So I went to the url you gave me. Below the video was a box that says "embed" - clicking that reveals a larger box just beneath with the following code:

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/qszVH0JCAYk?fs=1&amp;hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/qszVH0JCAYk?fs=1&amp;hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

Take this code into your post - but don't just paste it directly into the post. At the top of the post editor (or is it the bottom?) anyways, somewhere in there there's a tab that allows you to switch over to html view (revealing all your code for links, etc.) That's where you need to paste the video code. Then you can switch back to normal view and finish the post.