Apple has increased the time a user has to finish or rewatch a movie rented from iTunes from 24 hours to 48 hours for U.S. users, according to the company’s updated support document. Users in the U.S. users have 30 days from the time they rent a movie to begin watching it, and now they’ll have twice as much time to finish it. The 48 hour window to watch an iTunes rental has been available since the beginning of iTunes movie rentals in…