WordPress will display a video using the embed code you copy from YouTube or Vimeo, but there's a much easier way to embed video. All you need to do to embed something into a post is to paste the URL into the content area, on its own line and not hyperlinked.
For example, after pasting the following URL into this post...
...WordPress will automatically turned the link we inserted into this post into a Vimeo embed!
It also works just fine with You-Tube links as well, not just Vimeo!!