Um, I'm pretty sure that two companies conspiring to control an entire market is illegal. I'm no "lawyer" of course, but it sounds pretty sketch.
You know two companies can get together for the betterment of both and it is still not a monopoly right? That isn't "conspiring to control an entire market". Nothing and I mean NOTHING is stopping anybody else from renting you DVDs through the mail. Blockbuster ships DVDs to millions of customers for example.
http://en.wikipedia.org/wiki/CollusionIt's not a monopoly, but it's still illegal as far as I can see (if the allegations are true, of course).