Personally, i don't think they can catch all the illegal downloaders etc. Even if they did, another smart (like wise as in smart in bypassing the gov) person will just find another way to get illegal downloads going again. U idea is a great idea to track down ppl that illegally downloads. But finding IP addresses is only finding their internet address basically. (Isn't what IP address are? Ur address on the internet?) Correct me if i'm wrong. I'm only 14 for peak sake.
In my opinion, the gov should ban, delete, w/e, sites that holds programs that u can use to illegally download. To replace having lazy ppl getting up their lazy butts and walking to a store to buy movies w/e, have some kinda company hold legal downloads (but must pay so the ppl that made the movie, anime, etc won't lose any money)
(Like Wolf, forgive my lengthy response)