Questions about Youtube's Code and w3 Validator

Hi,
i've been browsing around YouTube and have a couple of questions:

1.With the embed code they give you is there even a need for the

<object width="425" height="355"><param name="movie" value="http://www.youtube.com/v/fd0wIYugi6g&hl=en"></param><param name="wmode" value="transparent"></param></object>

Code (markup):

part? Would the embed part be suffice for all browsers? Why do they provide this object tag for??

2. Why do they not use flash satay should we, or just forget about the validator?

3. Why do they close things like IMG and INPUT with a > and not /> ?? Does it depend on doctype?

You see i'm wondering whether to listen to W3 or Youtube!!

 

/> is a closing tag for xhtml while without the slash is for html.

Never forget the validator.