Free WebM Encoder is a simple utility that lets you convert your video files to the new WebM format. The program has an extremely easy-to-use interface. Just add the files you want to convert to the list (you can drag and drop them directly from Windows Explorer) and click the convert button. A variety of video formats can be converted, including AVI, MP4, FLV, WMV, and MOV.
Download and use it now: Free WebM Encoder