This video should work well in Firefox, Chrome/Chromium, and Opera. If you are using Internet Explorer, you may need to download and install the following plugin from Google:
Google Webm Plugin
Here, I am testing a streaming video that was taken with my iPhone. To do this, I converted the file from a .mov to a .webm:
.mov
.webm
# ffmpeg -i movie.mov -acodec libvorbis -ac 2 -ab 96k -ar 44100 -b 345k -s 640x360 movie.webm