magic file replacement & rented discs

[flyhigh]

forgive my ignorance. I'm trying to understand how this magic file replacement works. The description of the Magic File Replacement says "you can remaster any commercial movie disc using simple XML scripts." Does that mean that the original discs are somehow altered? If I rent an HD DVD from Netflix, is there a chance someone else has altered that HD DVD somehow? If so, what are the limits of what can be remastered onto those discs? Spyware, viruses, porn? Can I expect to find any of these things on rented discs? Could the movie itself be replaced or altered? It would suck to sit down to watch an HD DVD and the movie or parts of it are altered.

Thanks for answering a newbie question.

 

[Webslinger]

Could the movie itself be replaced or altered?

No. You can't write to commercially released discs (at all). You can just alter the order/manner in
which you view the material on the disc.