Some one once told me that Wal-Mart edits their DVDs, but that is retarded, and I have seen DVDs that were bought from Wal-Mart and they were not edited.
Also concerning the renting and selling edited movies, from what I understand they buy the originals and when you buy a disc from them you get the original disc along with an edited disc. It seems some people here are taking it to be that they are merely selling content edited bootlegs, which would never have lasted half as long as it has. Things like this have been around for a long time, there used to be places that you could take VHS movies to to be edited, I imagine they would just record over your original with their edited version (but I am not sure, perhaps they gave you a second tape). So if you look at the situation fairly, no harm is really being done to the video industry, they are still getting their money for the film, and the editing place is making a couple of bucks for distributing the films just like any other store that sells DVDs or rents them out. The only real difference is that customers are getting, along with their original DVD, a backup copy with material they find offensive edited out.
By the way, what is the official stance in the US about backing up your legally owned DVDs these days?