Please don't create multiple threads on the same topic. It just creates confusion in the forum and wastes time.
As for the URL it's very simple. You're on this web page right now; every page has a URL that is unique to it. If you look up to the top of your browser window you'll see a very narrow long box that has this in it:
That is the URL. To get the URL of any YouTube video, you go to the page the video is on, then in the URL window at the top of the page, you copy the URL, all of it. If you click on the YouTube URL I gave you above, it goes to a page with an Elvis Costello video. To make that video display in your blog, you just follow the instructions we gave you in the other thread, using that URL, the same one that's above, which is also the same one you'll see in the URL window when you go to YouTube.