A good source for beginning instruction and in addition to the very basics, including fairly good self-rescue demonstrations, it touches on related topics such as charts, navigation, weather, etc. The DVD is basic and there are many pertinent topics for the beginning sea kayaker that aren't mentioned, but what it does cover it explains clearly and effectively. Maybe start here and add some other sources that go more in-depth.
I also recommend the book "Sea Kayaking Safety & Rescue" for very in-depth safety instruction in even the most extreme conditions. Especially relative instruction if you're paddling in northern California as I am, as the author is based here.