Google Video started to display suggestions in the search box. The suggestions are identical to the ones used for YouTube probably because Google has a single platform for searching videos which is used by both YouTube and Google Video.
The number of suggestions is 5 and they can be disabled in the preferences page by selecting "Do not provide query suggestions in the search box".
So why use Google Video instead of finding videos on YouTube? Google Video indexes videos from hundreds of sites, many of the videos can be played without opening a new page and you can share them with your Gmail contacts.