People at Megaupload were uploading copyrighted things onto their servers at one point to gain traction. Like, company policy to go around and get stuff to put onto their servers.

If you follow takedown notices, there's no issue, DMCA's safe harbor provisions protect you totally. The issue was that Megaupload was participating in the uploading and stuff

(for the record: not condoning the federal gov't's usage of time/money trying to get Dotcom arrested/extradited or whatever)