Usage of subtitle files of copyrighted movies to get statistics about used words and their number count I know that there is a problem with creating subtitle files containing the original phrases (or even the translation of what has been said) and to release them. There are platforms, eg. OpenSubtitles, where you can download all these subtitle files. Even though the providing of these subtitles is not legal, I would like to get only the words and their count in the movie. If an developer sells an app, that uses a subtitle API, to retrieve the subtitle files for creating word-statistics about the movie, would this be a legal problem to any person involved? Is the developer breaking the law, because his app downloads the whole subtitle file temporarily to the users device? Is the user of the app breaking the law, because the app downloads the whole subtitle file temporarily to his device? Are the resulting statistics (words and their count) in anyway copyrighted?
The subtitles would be protected by copyright, in general. In the US, temporarily downloading the subtitle text to create statistics would, I think, constitute a fair use. It is transformative, it does not serve as a substitute for the original sub titles, and it does not harm the market for the film or for the sub titles. The existence of the API for the subtitles might or might not be evidence for fair use, depending on who supplied the data and under what terms. In other countries that have an exception to copyright for analysis and criticism, such a download might be held to come under such an exception. One cannot be sure until there is case law on the point, and I know of none. The ruling might be different in different countries. Statistics (words and their counts) about the subtitles for a particular film or video would be facts, and as such would not be protected by copyright at all. A text discussing those facts would be protected.
Addressing the question of programmer liability, generally speaking, a person who creates something that others use to infringe on copyright is not liable is liable if there are non-infringing uses for the thing (Sony). They can be liable if they intentionally contribute to infringement, viz Grokster one who distributes a device with the object of promoting its use to infringe copyright, as shown by clear expression or other affirmative steps taken to foster infringement, is liable for the resulting acts of infringement by third parties. End-user liability is different. In order to legally download (watch) anything, you have to have permission from the rights-holder, and from the site operator. The site operator will have terms of service according to which you can access material: if you violate those terms, you are infringing on copyright (you didn't do what the permission to copy required of you). If the site-owner knowingly distributes material without permission, he is an infringer and you have no legal license to copy (watch) that content, so you too are an infringer. If the site-owner unknowingly distributed material without permission and generally complies with the DMCA safe harbor requirements, he is not an infringer but you the user are. Congress has not created an innocent-infringement defense where you can defend yourself against an accusation of infringement by proving that you didn't know that the material was distributed without permission (there is an option to reduce liability for statutory damages to $200 in case of unknowing infringement, but not make all liability go away).
A document can be distributed under more than one license. Just because it has been made available under a CC license for free, doesn't mean that IEEE can't negotiate a different license with different terms that allow them to sell the content. (This is similar to the way that a software library can be available for free under a license that permits non-commercial use, but also be made available for a fee for commercial use.) If you want to know whether IEEE is legally selling Aaron Swartz's manuscript, you can contact Morgan &amp; Claypool, the publisher that owns the copyright, and ask them whether this use by IEEE has been authorized by them. For the other documents you mention, contact MIT Press. Etc.
Words themselves are not protected by copyright. Curated lists of words, however, are (what's protected is the artful collection of words chosen for a purpose). Hence Hasbro owns the copyright in the list of playable words, though it is a matter for future possible litigation to see if the courts agree. If you have permission from the copyright holder, that permission (license) should state how you can use the list (it does not matter if there is a title). However, you may need to obtain the list from the copyright holder. The website operator presumably already has a license, the terms of which may allow them to prevent you from copying from the website. E.g. the author may have granted the website operator the right to use the list as long as they don't restrict redistribution; but that license may also require restricting redistribution. So you also have to study the website terms of use – or get a copy directly from the copyright holder (assuming that that is the original author).
You probably can. There are a few questions here. First, is the message protected by copyright? In general, it probably is, but there are many exceptions that might allow you to use it without permission. Unfortunately, these exceptions vary from jurisdiction to jurisdiction. The exceptions tend to allow the use of small excerpts of a work for various sorts of purposes that don't undermine the copyright holder's ability to profit. That leads to the second question, which is why you are using that message. If you're including it in your source code so you can test whether a message generated at run time is in fact that message, that's one thing, and it's probably okay. On the other hand, if the owner of the copyright sells a database of all its message strings, and you're compiling a similar database that you also intend to sell, that's probably not okay. A third question concerns the Firefox license terms. It's entirely possible that they allow you explicitly to do what you're considering, in which case it doesn't matter what copyright law says about it. On the other hand, Firefox is open source software, and under some open source licenses, if you incorporate any of the source code in your own product, you are required to release your product's source code under the same license. If you're not already planning to do that, you should consider carefully whether including that error message would trigger that provision (if there is one) of Firefox's open source license.
The copyright on the book of quotations protects the collection. That is, it protects the author's choice of which quotations to include, and of what order to list them in. It also covers any division of them into groups or categories, and any added text (intros, comments, and so on) written by the author. It does not protect the quotations themselves. As those are not the original work of the author, s/he can have no copyright in them. Any quotes that are in the public domain (through expiration of copyright, or otherwise) may be used freely. Any others are protected by copyright. However the use of a short quotation is often fair use under US law, or is subject to another exception to copyright elsewhere. But that depends very much on the details of the factual situation. So quotes with expired copyrights are safe to use. Others may well be safe if they are relatively short, and proper attribution is given.
Details depend on the juristiction. For that, consult a lawyer if you plan to publish your app anywhere. But generally, even simple texts from exercises can be covered by copyright. Compare song lyrics, which are not much longer (and might not involve more creative thought than a good exercise ...). For vocabulary lists, it gets more tricky, but those can be covered as well if the assembly of the list was a creative effort. So if you simply list the 1,000 most common worlds in English and their translation, you are possibly fine, but if the words are divided into units and lessons, that's creative work.
Copying is illegal, creating an identical work by coincidence isn't. If it is not a criminal case, then a court decides whether it is more likely that the identical work was created by copying or by coincidence. Creating an identical work through a random process isn't going to happen, claiming this would be an awful defense. On the other hand, it is quite possible that two software developers using very stylized code adhering to struct coding conventions can produce quite large bits of identical code. Your links titled "metadata" and "hash" don't actually link to a description of metadata, or the description of a hash, but to a description of torrent files, which is something totally different. Systematically distributing files whose only purpose is the illegal duplication of copyrighted works should not be done without consulting a lawyer, as has been said on other threads (whether posting links to copyrighted files is legal). The chances that a random process will generate a file identical to an existing copyrighted file of say over 100 bytes are virtually zero. If there is an illegal copy of a copyrighted file, and you claim that you created it through a random process and coincidence, you will lose, and deservedly so.