Why does this youtube embed code stop working if I remove the embed tag?

I understood that the embed code had an embed tag inside the object tag as a fallback for IE and old browsers. But, if I, for example, take this code:

    <object width="400" height="336"><param name="movie" value="http://www.youtube.com/v/_25bsKcXw5o&rel=0&egm=0&showinfo=0&fs=1">
<param name="wmode" value="transparent"></param>
<param name="allowFullScreen" value="true"></param>
<embed src="http://www.youtube.com/v/_25bsKcXw5o&rel=0&egm=0&showinfo=0&fs=1" type="application/x-shockwave-flash" width="400" height="336" allowFullScreen="true" wmode="transparent"></embed>
</object>

And remove the embed:

<object width="400" height="336"><param name="movie" value="http://www.youtube.com/v/_25bsKcXw5o&rel=0&egm=0&showinfo=0&fs=1">
<param name="wmode" value="transparent"></param>
<param name="allowFullScree开发者_开发百科n" value="true"></param>
</object>

It doesnt display in Chrome or in Firefox. Why? Does this make sense to anybody? I've tried with several different videos, and the same happens with all of them.

The reason I am doing this is because I wanted to determine where should I change the youtube url attributes (to change behaviour of the player). After doing some more tests, I also noticed that Chrome is responding to he changes I do to the embed tag's parameters, and not to the object's...

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Here is a link to Adobe which explains the OBJECT and EMBED tags in detail.