[citation][nom]jimmysmitty[/nom]HTML5 though is a open standard but is still standardized. It works the same on FF4/5/6 as it does on IE9 but support for every part depends on the browser having it built in. IE10 is supposed to push even more HTML5 and CSS3 standards than IE9. In fact some of the new HTML5 tests on MS IE preview page wont open in IE9 because its a newer part of it.[/citation]
As any web developer will tell you just because html is standardized doesn't mean it will open identically on all browsers.
[citation][nom]jimmysmitty[/nom]Still for HTML5, the biggest advantage is being able to have video with no API. It can use h.264 right in the browser which will enable faster loading and better quality than Flash.[/citation]
Flash also supports h.264.