Update 2: The NY Times on the story: Post Office Drawback Cited in Dark Forecast for Netflix.
Update: Netflix spokesperson Steve Swasey responded that Netflix actually saves the U.S. Postal Service more than $100 million a year:
"Netflix pays first class postage for both the outbound and the return mail, but we do not use the USPS’s national network for return mail. We pick up the mail from post offices, saving the U.S. Postal Service more than $100 million per year. Netflix is in full compliance with U.S. Postal Service specifications. It’s unlikely we would be assessed any surcharges because we would modify the envelope if necessary. There have been 40-50 different iterations of the Netflix mailer over the years."
Barron's reports that the U.S. Postal service is considering a 17-cent per piece surcharge for Netflix DVD envelopes, Netflix: Postal Service Inspector General Proposes Applying Surchage To DVD Mailers.
An audit by the USPS released last month found that 70% of DVD mailers processed need to be handled manually because they “sustain damage, jam equipment and cause mis-sorts during automated processing.” The postal service estimates that it costs them an extra $41.9 million for extra processing over the last two years, and anticipates added costs of $61.5 million over the next two years. The recommendation: make the return envelopes machinable, or be subject to a standard 17-cent per piece non-machinable charge.
This seems to only affect Netflix's envelopes, as "Wible also contends that Blockbuster’s (BBI) mailers are not prone to the same issues.
You can read the full audit report by Tammy L. Whitcomb, Deputy Assistant Inspector General for Revenue and Systems.