Posted as per the instructions in the Codex . . .
Vidéos
Post Format: Video (VideoPress)
[wpvideo tFnqC9XQ w=680]
VideoPress, especially as a video post format, usually provides some unique styling issues.
You will need to install Jetpack or Slim Jetpack plugin to turn the shortcode into a viewable video . . .
Post Format: Video (YouTube)
Learn more about WordPress Embeds . . .