HTML5 video

HTML5 video is an element introduced in the HTML5 draft specification for the purpose of playing videos or movies[1], partially replacing the object element.
Adobe Flash Player is widely used to embed video on web sites such as YouTube, since many web browsers have Adobe's Flash Player pre-installed (with exceptions such as the browsers on the Apple iPhone and iPad and on Android 2.1 or less). HTML5 video is intended by its creators to become the new standard way to show video online, but has been hampered by lack of agreement as to which video formats should be supported in the video tag.

Supported video formats
The current HTML5 draft specification does not specify which video formats browsers should support in the video tag. User agents are free to support any video formats they feel are appropriate.

Default video format debate
Main article: Use of Ogg formats in HTML5
It is desirable to specify at least one video format which all user agents (browsers) should support. The ideal format should:
Have good compression, good image quality, and low decode processor use.
Be royalty-free.
In addition to software decoders, a hardware video decoder should exist for the format, as many embedded processors do not have the performance to decode video.
Initially, Ogg Theora was the recommended standard video format in HTML5, because it was not affected by any known patents. But on December 10, 2007, the HTML5 specification was updated, replacing the reference to concrete formats:
User agents should support Theora video and Vorbis audio, as well as the Ogg container format.
with a placeholder:
It would be helpful for interoperability if all browsers could support the same codecs. However, there are no known codecs that satisfy all the current players: we need a codec that is known to not require per-unit or per-distributor licensing, that is compatible with the open source development model, that is of sufficient quality as to be usable, and that is not an additional submarine patent risk for large companies. This is an ongoing issue and this section will be updated once more information is available.
Although Theora is not affected by known patents, companies such as Apple and (reportedly) Nokia are concerned about unknown patents that might affect it, whose owners might be waiting for a corporation with extensive financial resources to use the format before suing. Formats like H.264 might also be subject to unknown patents in principle, but they have been deployed much more widely and so it is presumed that any patent-holders would have already sued someone. Apple has also opposed requiring Ogg format support in the HTML standard (even as a "should" requirement) on the grounds that some devices might support other formats much more easily, and that HTML has historically not required particular formats for anything.
Some web developers criticized the removal of the Ogg formats from the specification. A follow-up discussion also occurred on the W3C questions and answers blog.
H.264/MPEG-4 AVC is widely used, and has good speed, compression, hardware decoders, and video quality, but is covered by patents. Except in particular cases, users of H.264 have to pay licensing fees to the MPEG LA, a group of patent-holders including Microsoft and Apple. As a result, it has not been considered as a required default codec.
Google's acquisition of On2 resulted in the WebM Project, a royalty-free, open source release of VP8, in a Matroska container with Vorbis audio. It is supported by Google Chrome, Opera Browser and Mozilla Firefox.