Use of Ogg formats in HTML5
, HTML5 video is not currently as widespread as Flash videos, though of recent rollouts of experimental HTML5-based video players on websites, DailyMotion is so far the only one to use Ogg Theora and Vorbis formats, which suggests an increasing early interest in adopting HTML5 video.
HTML
The Document Type Declaration is for HTML5. If a declaration is not included, various browsers will revert to "quirks mode" for rendering.