The basic idea is to paste the video only into the page’s HTML code while editing in Visual mode, select it and unlink it with the Unlink button. This removes the link, so instead of https://www.youtube.com/watch?feature=fvwp&v=W2BM8ZJXOds&NR=1 you will suddenly have https://www.youtube.com/watch?feature=fvwp&v=W2BM8ZJXOds&NR=1 , and if you put it on a new line, the video will be embedded right in your post, also on a new line:
I am writing this because I searched in vain for a button to insert YT videos into WordPress posts, until Martin nudged me that WP must be able to do it and sent me this link , which describes in more detail all the tricks you can do with an embedded video. It could not be any simpler, and once again WP pleasantly surprised me :). Good luck, perseverance and great ideas with your blogging!