Now it has become very easy to display a video as background in your WordPress based website but make sure it uses a lot of bandwidth so you should have a good hosting.
You might have noticed in some websites that shows an icon on the side of the document or file link. PDF icon is most common and widget used icon on links directing to PDF. Now by using MimeTypes Link Icons plugin you can automatically convert your file links to their icons. The plugin covers a long list of supported file extensions where it would be showing the icons automatically.