And yes, there is a movie looping. In recent times and potterings I am using the wonderful mb.YTPlayer Plus! and mb.vimeoPlayer PLUS! jQuery components to set different videos for the background. Looks very cool, but this code will not work on devices. And since I want my page to be without (m)any custom design fallbacks I returned to the Dudley Storey approach.
transform: translate(-50%, -50%);
His article is great reading and covers some considerations and limitations on the subject as well.