You can no longer possibly upload videos to Google Videos but it is still possible to access the videos that were uploaded before that date. But Google has just sent an email to every user of the service to prevent the database from Google Video would cease to exist in short videos will disappear.
After May 13, 2011 the videos will disappear from Google Video on the web. Google encourages people who uploaded videos to download them and move to youtube off course.
Still, the url video.google.com (and different versions for different countries) will remain active as a search engine for videos.