Here is a URL or address of a YouTube video:
http://youtube.com/watch?v=pmOmT7a8NB4

The video ID (the part we need) is bolded:
http://youtube.com/watch?v=pmOmT7a8NB4

Sometimes there will be additional stuff after it like this:
http://www.youtube.com/watch?v=pmOmT7a8NB4&eurl=

But we still only need this part in bold:
http://www.youtube.com/watch?v=pmOmT7a8NB4&eurl=

After we take that part out we put "youtube" (no quotes) in curly brackets {} before it and /youtube (no quote) in curly brackets {} after it like so:

Code:

And we get this: Clear as mud? Great, just post a link and I will fix it for ya!