Here's a great site from Canada's Astral Media that offers video education and testimonials on PPM.
It also includes PDF versions for each presentation, and it's aimed at advertisers first and foremost.
I like the way Astral leverages the educational advantages of digital media – using audio, text, and video – to make its points.
Does your U.S. broadcast group do this?
A good illustration of how radio is more than sound nowadays.