Now that the html code is placed where you want it, go back to visual mode.

When your editor shifts to visual mode, you should see a gray box where the video has been placed, like this:

Now, I am working with a test draft post, so there is no content to speak of. But I want to know if the video is going to be sized properly with the layout of my published and viewed page and, in most cases, for me, that means it is the full width of the text content paragraph. So for testing and comparison sake, I will key in enough text to more than complete a full width paragraph in visual mode, as such:

If you are placing a video in a post that is already filled out with content, you can of course skip that small step, but in either case, now you want to know how it will actually look on the viewed page, so at this point, click on "Save Draft"

Then click on "Preview Post"

Now you will see if the video looks well balanced on your viewed page. If so, great, you are ready to publish, if not, you can resize as needed. Both of these cases will be covered on the following and last page.