The code you posted looked like this:
<object width="425" height="355">
<param name="movie" value="http://www.youtube.com/v/nIHn7bWfMkA&hl=en&rel=0&color1=0x3a3a3a&color2=0x999999">
</param>
<param name="wmode" value="transparent">
</param>
<embed src="http://www.youtube.com/v/nIHn7bWfMkA&hl=en&rel=0&color1=0x3a3a3a&color2=0x999999" type="application/x-shockwave-flash" wmode="transparent" width="425" height="355">
</embed>
</object>
It should look like this:
http://www.youtube.com/watch?v=uh8KVG8j68I
Do not use the embed flash code. Copy the URL from the address box in your browser and put it between the YouTube tags.