There is a tool on the net that make your life easy.

http://www.htaccesstools.com/hotlink-protection/

But we can't disallow the blank refers because the vshare player design.

and the reason is that the player begins with.
Code:
so.addVariable("file","http://mysite.com/flvideo/1210779023428305516.flv");
it must be like this
Code:
<script type="text/javascript">

	so.addVariable('file',"1210779023428305516.flv"); :D 

</script>
if someone can acheive that then can disallow blank refers. :idea: