Standardized YouTube embedding code in XHTML (also validates as HTML5)
<object type="application/x-shockwave-flash"
data="http://www.youtube.com/v/L2tuL_2Q3vA?version=3&hl=en_US&rel=0" width="724" height="436">
<param name="movie" value="http://www.youtube.com/v/L2tuL_2Q3vA?version=3&hl=en_US&rel=0" />
<param name="allowFullScreen" value="true" />
<param name="allowscriptaccess" value="always" />
</object>
Standard-compliant YouTube embedding in HTML5
<iframe width="560" height="315" src="http://www.youtube.com/embed/vopjMojmXzE?rel=0">
</iframe>
