Nice job on the Cross!!
I believe you would want to have the video "hosted" somewhere first like you tube, could also be on another server, but I don't think you can use the link from Facebook??. Then would post the following code to embed the video in the post.
<embed width="420" height="345" src="http://www.youtube.com/watch?v=XGSy3_Czz8k" (This would be the you tube hosting link of you actual video) type="application/x-shockwave-flash"> </embed>
There are several other ways to accomplish this as well, but the you tube route is pretty easy