Silverlight 4.0

Microsoft Silverlight is a free web-browser plug-in that enables interactive media experiences, rich business applications and immersive mobile apps.
Silverlight offers a flexible programming model that supports AJAX, VB, C#, Python, and Ruby, and integrates with existing Web applications.

Silverlight supports fast, cost-effective delivery of high-quality video to all major browsers running on the Mac OS X or Windows.

Windows? Check. Mac? Check. Linux? Check. Silverlight works on all major OS's plus all major browsers, including Firefox, Google Chrome, Safari, and yes, Internet Explorer.