Cut and paste the URL (the adress for the video),and use the link button on top of your messagebox when you write your post.
http://s723.photobucket.com/albums/w...t=DSCF2889.flv
Edit,you dont have to do that,just put the URL in the messagebox and it will convert to a link automatically
Thats what i did in this post.You dont get the picture-link though