• Audio

  1. Audio tags are invisible by default.
  2. 
     unless you specify controls="controls"
  3. http://www.w3.org/TR/html5/video.html#audio

• Video

  2. The video tag behaves similarly to the audio tag. This video is H.264 encoded.
  3. http://www.w3.org/TR/html5/video.html#video
  4. http://www.youtube.com/watch?v=vdQj2ohqCBk (source)