Ok, I reckon I can justifiably download something if:
1. I have paid for it before.
Bought it, rented it, paid to watch it in a theatre. If I gave my friend Joe $2 to loan me a copy of his DVD rip then that doesn't count, but any bona fide agent which I have good reason to believe has an arrangement with the studio to compensate them for my viewing counts as a-ok. Ok in theory, I shouldn't watch it with someone who has never paid to see it or loan it to them.
2. Material made available to the public domain.
If it's in the library then I can download it. The only thing that changes is that I save the drive to the library & that's good for the environment

. If Braveheart is going to be on TV but there is a lightening strike and the power goes out, I feel ok about downloading it and watching it the next night. You could argue that I should have to stop every 20 minutes and go watch some commercials, but I see and hear enough commercials already each day that supplementing them is absurd.
3. Culturally significant material.
If I want to listen to some Mozart concertos, I could go to the library and get them. But say I lived in Concord, Massachusetts and wanted to read Twain's Huckleberry Finn and find that it is banned (although it's probably not banned there anymore). I don't think my government has the right to determine what I should be allowed to read, nor are they the final word on what is culturally significant. I will make that determination for myself.
This does not open the door for willy-nilly downloading imo. The latest Beyonce recording or whatever is indefensible as being culturally significant since it simply hasn't been around for long enough to make an impact.
Consider also that a kid in a poorly funded municipality with a shitty library has just as much of a right to familiarize himself with, for example, the evolution of classical music as does a kid living near a kick ass library with an extensive collection. Sony would disagree. Similarly, a kid from a rich family who buys him culturally significant material which is not found in the library does not have a greater right to education (although he usually gets one) than a kid from a poor family who cannot afford to buy the same things. The rich kid and the poor kid have the same rights.
This is sort of an aside but... there are some great fuckin' movies out there that are simply not available anymore in some places. For example, My Dinner With Andre. This movie deserves to be kept alive even if video stores disagree and the studio which put it out doesn't find it profitable to print any more copies. Some things should be downloaded and shared to ensure their availabilty to others. An argument against downloading is frequently made that it violates 'the rights of the artists' but I would bet that a true artist would applaud the continued existence of his work when businessmen who hold the legal rights to its distribution deem it to be no longer profitable.
What is culturally significant is open to debate but since this thread (and the wide world of downloads) is about personal justification, it is up to each person to honestly make that determination.
4. Educational material in general.
Knowledge should be available to anyone who wants it. Will Hunting was wrong - your library will not provide a university level education. At least my local library wouldn't, it is a pain in the ass compared to google, and audio and video stuff available online give a busy person a better opportunity to learn than do more time consuming books.
I regularly rip off lectures recorded in university lecture halls. I am now listening to "Introduction to Ancient Greek History" which was recorded at Yale and I will tell you that it is a good thing I didn't try to go to Yale. If by some miracle they let me in, my ass would be filling a seat which should have been filled by a much wiser ass than my own and it would be unjust that I got the seat instead of them. However, I have the same right to that information as a Yalie (whether I have the capacity to take it in and understand it is my problem).
I am grateful to the company which recorded it for setting up a mic on those days and if they had a donations option I would make use of it. As it is, I plan to buy a series or two from them, but I will do this out of gratitude rather than obligation. I reject the idea that knowledge in any form is something which has to be paid for, by attending Yale or by purchasing the lecture, so that your right to knowledge increases with the size of your bank balance. I therefore make no distinction between a course made freely available by a university (although it's awfully cool of them to do so) and one put out by a company as a copyrighted item, and I download them both without guilt.
Not to shoot out too far on a tangent, but I think this is really the point of the internet. Throughout history, only a select few had access to information. The decentralization of knowledge which the internet affords us means that information is (or should be) freely available to anyone who wants it (I mean information for the purpose of education, not all information without exception, including trade secrets, classified government stuff, etc). This is the first time in history that this has been the case. I think that is truly awesome and I would permit no roadblocks if I had my way. I would like to see much more stuff find its way out there, since there is nowhere near enough information for someone to achieve the equivalent of a uni degree, but what is out there is usually very good and I plan to make full use of it. Which is the greater injustice - that Yale University or a company which sets up a microphone to record what is said there make a lower profit, or that everyone who wants access to first class information has to settle for second rate stuff or go entirely without because they can't afford to pay for it? The right to education supersedes intellectual property rights imo.
Nevertheless, I plan to buy some lectures too and when I do I will be seeding them, so keep an eye out.
