The user doesn't need any plugin to view the video, but their browser must support HTML5
However the web server hosting the page will need to be setup to stream the video content.
This is as simple as adding mime type on the web server.
Adding Mime Type - on webserver - .mp4 Video/mp4
To add .mp4 MIME type in IIS on Windows 2003 Server
Select the site to configure in IIS, right click and select "Properties"
Under HTTP Headers Tab, select "File Types" under the MIME Map section and select "New Type"
Type " .mp4" as the associated extension and "video/mp4" as the content type.