I imagine that it would depend on whether it's "commercial" or "home grown." There may be a way to embed home video, but as a simplified method I would recommend uploading to YouTube or Photobucket (or some such thing) and then copy and paste the HTML code from the site into a post.
I ain't no geek, I ain't no nerd. I'm just an old fart who's picked up a trick or two over the decades.