I think you can embed the video if you follow the notes I made here: Letter Head HTML / Table Setup - #2 by MichaelPinkowski (Substituting the Blog Post DocType for Letterhead in this example.)
But it will probably be a one-way street. If you try to switch back to the Markdown editor you might lose the embedded code. I am sure you will lose it if you switch back to Markdown and then open that post.