Watch the video and then read the transcript.
More details about wave power in this Greenpeace video : Wave power : how it works. (All the Greenpeace videos on YouTube might interest you) You can also have a look at a brochure about the Pelamis system (click « PELAMIS BROCHURE » at the bottom of the page.)
Watch this programme (BBC Channel 4 News, April 02, 2008) : Marine Current Turbines (Strangford Lough, Northern Ireland)