WebM video files play directly in your web browser using a new technology called HTML5. No plug-ins are required, but you must install a web browser that supports WebM files.
Whats great about WebM video is that its a very high quality video,which has a great video playback performance, even on older computers. It’s also 100% free, open to everyone and supported on popular video sites like YouTube. It supported web browsers like Mozilla Firefox 4, opera 10.60, Google Chrome 6 and Microsoft internet explorer 9.The easiest way is downloading a rough developer-oriented test version of two browsers that will have support built-in: Firefox and Opera. Programmers have been working to add support for some time, but only made the changes public after Google’s announcement.
The open-source project behind Google Chrome, Chromium, has been updated with WebM support, but it’ll take until May 24 for it to sift into the developer channel of the Chrome browser for convenient testing. Apple has been mum about its VP8 and WebM plans, but it’s a big booster of H.264. Microsoft, another H.264 fan, has said its future IE9 will support VP8 if somebody takes the trouble of installing software to enable it.