In this great Mashable article, Catherine-Gail Reinhard identifies five outstanding Youtub-ing brands.
While commending big glossy one like Quiksilver and Nike, Catherine also calls out the humbler efforts of brands like the University of Phoenix.
The point is, it's not about being big and flashy, but about being committed, true to 'thine own brand' and a publisher of regular, entertaining content that has inherent value for a specific community.
Somehow she manages to make it sound so easy, yet very few brands get it right.
Well worth a read.