Video is one of the most efficient tools of visual communication

Since its early days, video has been one of the most powerful and efficient tools of visual communication. It is able to deliver a direct and clear message to a broad audience as well as focus viewers on something particular. A visually appealing video is an excellent way to present a product, service or brand and take user experience to a much more interactive level. For this reason, elegant, creative and professional videos are becoming increasingly popular in Web design today.
Some designers go even further, creating Bluray-like experience in the browser, with interactive navigation menus, soft transitions and exceptional visual effects — all supported with background videos. This can be done with Flash or HTML5, however, most websites incorporate background videos using only Flash. To enable the rich cross-device experience, it is worth considering adding fallback-videos for those users who have a browser that does not support Flash. Nevertheless, we didn’t want to go into technical details just yet and wanted to see what actual approaches designers take within their websites.
The performance of a website including a background video depends significantly on the speed of the user’s internet connection. Video backgrounds certainly do not fit in every setting; they wouldn’t be meaningful in online magazines or blogs. However, they can work really well in entertainment and certain corporate settings which are supposed to communicate artistic qualities, exclusivity, branding or even high quality standards. As you will see, they work very well in portfolio websites, fashion websites and promotional campaigns. Below you’ll find a showcase of good and not so good websites that implement this dynamic eye candy at full screen.

This is a great article posted by Aygul Zagidullina on the Smashing Magazine website which goes on to provide lots of examples.

You can read the full article here: Creative use of background video