[DarkShikari]

Disclaimer: IANAL.

Answer: Of course it's probably illegal. A fair use argument could theoretically be made, but I don't think there's been an actual court case over it, so I would put any such argument in the "dubious" category.

But in practice, most publishing companies don't care; in some cases they will even support your actions. The only exception is when the original text is the work in and of itself, such as with translating novels. Legal threats have been thrown around in that case, particularly in the case of American companies licensing foreign works and then threatening fan translators who had been working on translations independently (see the "Support JAST USA's official localizations of Nitro+ games!" fiasco in which many translation groups were sent takedown notices).

That's pretty much the only case in which legal threats fly around period, as such companies view fan translations as a threat to their profits, while the original company who made $movie would love for more people to buy it, regardless of the language in which it is purchased.