If you have a title with subtitle(s) and other metadata associated with the section or article, place both the <hgroup> and the metadata within a single <header> element.
If you have a title with subtitle(s) or tag lines (i.e., more than one consecutive <h1>–<h6>), group them in an <hgroup>.
When grouping headings in an <hgroup> element, the outline algorithm will mask the lowest level all but the highest level heading in the group from the resulting document outline.
It can only contain a group of <h1>–<h6> element(s), and it should be used for subtitles, alternative titles, and tag lines.
If you don't already know, the hgroup element is obsolete in HTML5.
Advice is now provided in the HTML spec on how to mark up subheadings, subtitles, alternative titles and taglines using existing and implemented HTML features.
The solution for now is to produce your videos in multiple formats.
Table 1. Browser support by video format
Browser
MP4
WebM
Ogg
Internet Explorer 9
Yes
No
No
Firefox 4.0
No
Yes
Yes
Google Chrome 6
Yes
Yes
Yes
Apple Safari 5
Yes
No
No
Opera 10.6
No
Yes
Yes
Note: For the latest compatibility information, always check the CanIUse website.
A more robust way to create the fallback is to use a JavaScript utility like Modernizr to evaluate the browser's capabilities and then dynamically write the video and source tags or embed the Flash video player using SWFObject.
Tip 3: The source tag should always include the "type" attribute with the correct MIME type value. You may need to add an .htaccess file to your server to define the MIME types as well. Check out the Video for everybody article for more tips on MIME types.
Tip 2: The video tag includes a range of parameters that you can use to configure the video. See the Mozilla article Using HTML5 audio and video for more information.
Tip 1: The Adobe Media Encoder does not currently export video to Ogg or WebM format. You can use the Firefogg add-on for Firefox to encode video to Ogg Theora format, or you can use Miro Video Converter to encode video to WebM or Ogg Theora format.