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.
Adobe Flash
Firefox (from version 46) rewrites old Flash-only YouTube embed code into YouTube's modern embedded player that is capable of using either HTML5 or Flash. Such embed code is used by non-YouTube sites to embed YouTube's videos, and can still be encountered, for example, on old blogs and forums.