它有experimental support in a number of browsers。@H_301_3@

原始答案：@H_301_3@

从HTML5 spec(写作时：09年6月)：@H_301_3@

User agents should not provide a
public API to cause videos to be shown
full-screen. A script,combined with a
carefully crafted video file,could
trick the user into thinking a
system-modal dialog had been shown,
and prompt the user for a password.
There is also the danger of “mere”
annoyance,with pages launching
full-screen videos when links are
clicked or pages navigated. Instead,
user-agent specific interface features
may be provided to easily allow the
user to obtain a full-screen playback
mode.@H_301_3@

浏览器可以提供用户界面，但不应提供可编程的。@H_301_3@

请注意，上述警告已从规范中删除。@H_301_3@