If you want to put your video files online using HTML5 then it's recommended to have three different formats for a full browser support. Those formats are mp4, ogv and webm.
Check out unique 360-degree view of the Hafjell MTB World Cup track. Use the up/down/left/right cursor keys of your keyboard or click and drag with your mouse on the video player.
Really great and free service where you can chat using a bunch of services like Skype or Google Talk within your web browser, meaning you don't need to install anything on your computer.