I found a really nice website that shows real beauty of HTML5. Some pages uses HTML5 video background feature. There is some drawbacks like high CPU usage when playing huge HD video in background,but I am getting quite stable ~30FPS on Google Chrome 19.0.1084.46 with GPU acceleration enabled in hidden settings. 
For video playback I found a powerful open-source solution - VideoJS which has a fallback to Flash player if user browser doesn't support HTML5 <video> tag. It's easy to setup and supports custom player skins. And for making a video from scratch I found a free video editor/maker Wax . You may need to mark compatibly with Windows XP if your are using latest Windows version since the latest Wax version was released in a year 2005.  
If you are getting error: "No file i/o filter was able load the give file(s)"  than you need to make sure there is no duplicate library files in system folders that Wax is using. 
I solved this problem by simply deleting "DevIL.dll" from Windows/System32 folder. If that doesn't help make sure there is no "DevIL.dll" and "zlib.dll" in Environment Path. 
Environment Variables on Windows 7
Environment Variables on Windows XP

Update:
Now you can buy  a full pack of 14 HD videos for HTML5 Video background element.