After a string of bad luck for YouTube, with deals falling through the cracks left and right (such as with Warner and CBS), they managed to turn it around a bit. The BBC is working together with YouTube to prove three channels, including two entertainment and one news channel, on the service. The entertainment venues will have no advertisements, but will primarily feature trailers and short features rather than full shows. The second channel will "self contained clips" and have advertisements. The BBC is not looking to push content through YouTube, however, and seems them as more of a teaser site to attract people to their "real" service:

The BBC's director of Future Media and Technology, Ashley Highfield, said the deal was "not about distributing content like full-length programmes; YouTube is a promotional vehicle for us".
Interestingly enough, they are also claiming they will not be hunting down copyrighted material that came from the BBC. In fact, they even mention they may swap poor-quality content for higher quality content, citing that even the pirated material can be good promotional material.