HTML5 Video Tutorial
The good news is that with the <video> tag you no longer need plugins. The not so great news is that at the moment different browsers support different formats. If you are going to use the <video> tag, it is best to offer different versions of your video so that the browser can choose the appropriate one.
-> See live example Here
There are three formats that are supported by different browsers. They are:
Ogg/ogv (Theora video codec and Vorbis audio codec)
MPEG4 (H.264 video codec and AAC audio codec)
WebM (VP8 video codec and Vorbis audio codec)
Here is an example of a how to post a video with a fixed width and height. The example as you can see also allow for a control bar and automatic looping of the video.
<video width= "320px" height= "240px" controls= "controls" loop= "loop" >
<source src= "multimedia/nebula.ogv" />
<source src= "multimedia/nebula.mp4" />
As of now the style and resizing options (fullscreen/pop out) are browser dependent. Here is what the video will look like in a browser that supports the HTML5 <video> tag. (The example is just an image not a working video file.)
Take a closer look at the Video Tag Attributes.