#t=3m05s
at the end of the url, should make the video play @ 3 minute 5th second.
In this example the url is present, but it doesn't start from the 9th minute. The video, however, plays fine. The question is why?
<iframe id="Iframe1" type="text/html" width="640" height="390"
src="http://www.youtube.com/embed/EgBWDPXF2gU?autoplay=1#t=9m05s&origin=http://example.com"></iframe>