Produced in 2008 by the Denver International Airport communications staff. Actually has a section at 4:13 that discusses the conspiracy:
If you’re not in the terminals or on the concourse, where else would you be? A secret underground city perhaps? Some people thing there’s a conspiracy making our airport the center of the New World Order. Rest assured this story is definitely a myth. Besides if it were true, Geraldo would have already sniffed it out, don’t you think?