A few months back the filmmakers Carl Deal and Tia Lessin got some bad news. The PBS funding that they had counted on to complete their documentary on campaign financing was being withdrawn. This setback came not long after PBS took the unusual step of warning David Koch (of right-wing billionaire donors “the Koch Brothers” fame) that he had been negatively portrayed in another of the networks documentaries, and giving them a chance to respond.

Lessin and Deal had good reason to believe that their setback was closely related to that incident. The name of their film? “Citizen Koch.”

Lessin and Deal found other funding and completed their movie, which was released on Friday, June 6. It’s a highly watchable and engaging documentary that uses Koch-funded Wisconsin Gov. Scott Walker’s calculated war on unions – which was straight out of the Koch Brothers playbook – as the narrative thread for a broader exploration of the corrupting influence of money in politics.

Tia Lessin told us about their experience with PBS on “The Zero Hour” last month, and also gave us some background on the film. The video of that interview can be seen above.

Jane Mayer of The New Yorker used the tale of Lessin and Deal, and that of fellow documentary filmmaker Alex Gibney, to tell the tale of corporate wealth and its growing influence on the inner workings of PBS.

That is an important story that more Americans need to hear. After decades of seeing it attacked by the right wing, most Americans probably consider PBS a bastion of liberal thought – that is, if they think about it at all. The truth is that years of funding cuts have led to an increasing reliance on billionaires and their foundations. As a result, PBS (and its radio equivalent, NPR), while continuing to broadcast a great deal of fine programming, has increasingly come to reflect the agenda of “the one percent.”

This troubling development is also reflected in David Sirota’s reporting on wealthy investor John Arnold’s funding for a PBS program that repeated disproved talking points from billionaires who are hostile to public pensions and other publicly funded retirement systems. (Anti-Social Security billionaire Peter G. Peterson is married to Joan Ganz Cooney, who founded the Children’s Television Workshop.) Sirota’s article, amusingly entitled “The Wolf of Sesame Street,” led to the network returning Arnold’s money.

But the problem still persists. The Public Broadcasting System isn’t really public anymore – at least, not to the extent it once was. Tia Lessin and Carl Deal have made an excellent documentary that is well worth seeing. (The trailer can be viewed here.) They have also, unintentionally, cast a spotlight on the fact that yet another independent news source is falling under corporate influence.