In the aforementioned video Matt Cutts also states that it is preferable if the site has absolute urls for its internal links. But having absolute internal links will slow your site's load time and also prevents the owner from changing domains without changing all of the links. The owner may not want to change domains but most often when a site is in creation it is tested on the web designer's domain, this would not be possible if the internal links were absolute. I have checked a number of sites that have high page rankings and find that most have internal links that are relative. Even companies where the creation and testing of the site would most likely be done in house. Two such sites are Apple and W3C.