Before Google bought Youtube; before Google Video was a search engine; Google Video hosted its own videos. According to an announcement (which, as far as I can tell, has only been made via email so far), they'll be disabling playback on 4/29. They've put a download button up which will remain functional until 5/13.

While GV doesn't have the presence here it did a few years ago, there's probably still quite a few videos which will go dead later this month, particularly documentaries, I'd think.