I didn't read all of the instructional .pdf but it seemed to be covering the process of embedding or linking to media. That is not the same as what you are trying to do which is show the linked media within the bounds of the .pdf page.
I played with this in Acrobat 9.
The problem is to get the actual address of the .swf movie in YouTube.
This is being handled by a swag of .php, .css and other files.
If you open:
+Safari > Menu View > Activity+
You will see what is being loaded on the YouTube page. The .swf file will be the largest by far and will grow progressively. If you double click on the .swf name in the Activity list it will briefly show the actual address then DL it.
On my machine this happens so fast that I do not get a chance to capture the address which is otherwise truncated in the Activity list.
I tried taking the Shared address and pasting this into Acrobat's media dialog but it doesn't like it either.
Try going over to Adobe's Acrobat forum:
http://forums.adobe.com/community/acrobat/acrobat_macintosh
…and see if you can find someone to get around this.
Sorry I couldn't help more,
Peter