Default code is:
HTML Code:
<iframe width="420" height="315" src="//www.youtube.com/embed/BpqNvskS_kM" frameborder="0" allowfullscreen></iframe>
You don't need
&fs1 for the iframe.
allowfullscreen, for whatever reason, puts it in there. Supposedly,
allowfullscreen will pass validation now.
But yeah, your problem was probably that you were using
v instead of
embed.