HTML5 Video

<video controls="controls" poster="URL of poster image">
  <source src="mVideo.mp4" type="video/mp4">
  <source src="mVideo.webm" type="video/webm">
  <source src="mVideo.ogv" type="video/ogg">
    Your browser does not support the HTML5 Video element.

Here’s is a pretty good online video converter if needed:

What formats to use:

Safari, Chrome and IE9
H264 video codec, AAC or MP3 audio codec and .MP4 as the video container.

other browsers
Theora video codec, Vorbis audio codec and Ogg video as the video container (Ogg-Theora combination).