By using WebM DirectShow Filters you will be able to encode and decode VP8 video, and to create and play WebM files.
By installing these filters in your system, all the applications that are based on the DirectShow, such as Windows Media Player, will be able to render and encode WebM files.
Additionally, you will have to install Vorbis audio support.
The WebM format is open and royalty free and it refers to video and audio streams and to the file’s structure.
The file structure is based on the Matroska container. WebM video streams are compressed with the VP8 video codec, while audio streams are compressed with the Vorbis audio codec.
WebM for IE9
is free software that enables support for playing WebM videos in Microsoft Internet Explorer 9+ on Windows 8, 7 and Windows Vista.
This application is part of the WebM Project, a collection of tools for creating and publishing content in the WebM format.