In addition to support for HTML5 <video>, Microsoft also plans to introduce the browser’s new User-Agent (UA) String on top of the
Platform Preview release of Internet Explorer 9. And as it is the case for HTML5 <video>, the new UA String will be delivered through an update to the Windows Internet Explorer Platform Preview, which, according to Microsoft, will be refreshed at least once every eight weeks, ahead of the Beta development milestone.
An important change for site developers to know is that IE9 will send the short UA string by default. This change improves overall performance, interoperability and compatibility. IE9 will no longer send additions to the UA string made by other software installed on the machine such as .NET and many others,”
Marc Silbey, IE program manager, revealed.