I think what he's getting at is the following...
That Megaupload pays some people on 3rd party sites specifically to upload illegal content onto the Megaupload site and to provide links to that content on those 3rd party sites. This then drives traffic to megaupload and hopefully encourages people to pay for their subscription service to be able to download all the content, while at the same time allowing megaupload not to have to advertise said illegal content on their site directly or make it easily accessible.
By paying the 3rd party people to upload and advertise it on the 3rd party sites, it essentially makes it to where megaupload (if the payments weren't discovered) could claim that they weren't promoting the use of their site for illegal content because they weren't advertising it or providing easy ways for people to find it.
Lets put this a different way (Based just off the charge).
Lets say you have a shop that sells stuff that useful for doing drugs, but those items themselves aren't illegal. They are sold as art pieces or tobacco pipes or other sort of things. This shop can't go out and go "Hey, come by our pipes, its great for smoking pot!" because they'd actively be promoting that their stores items are to be used for illegal activities.
However, to get around this, they go to a few drug dealers and go "Look, we'll pay you all $X amount of dollars a month. What we want you to do is use the area around our store as the location to do your transactions so that the people will then be likely to come in here and buy the supplies they need".
Essentially, using this 3rd party to attract the customers to their store to use them for illicite purposes.
Not a perfect analogy but that's kind of what they seem to be alleging in this case...right redress?