Actually a lot of people use cracks to not have to put the disc in the drive every time. Also some people have had to use a crack to even run this game because the Securom won't let it load for one of 100,000,000 reasons. Also... a lot of games simply run... BETTER... if you use a crack that stops the game from trying to re-check the disc every 30 minutes or verifying files while you're in the middle of playing... just to cover a couple of things.
Second, he did NOT say he was running it off a USB hard-drive, he said that his USB drive was at his cousin's in response to the idea of putting the clean GTA IV installation on a 16Gb Thumb-Drive so as to not have to uninstall/re-install every time.
yup im one of them, i use a crack to save the wear and tear on my origonal game disc's.i had to buy 2 san andreas games due to my first game disc getting too scratched to read anymore.