Well the fact that MMF is ultra-touchy about it is largely because he was pm-ed a massive spoiler for no more reason than spite.
I can see their point - when Dany finally starts speaking Valyrian it was a big moment and someone who had read the book
spoiled it.
I know most only want to help clear up what is going on, and being helpful like Hemi was can be laudable; I don't think there was any harm in what he posted. But too often things like "helping" ends up as a spoiler. Either because of too much "help" being given, or because with the differences between the book and series the release of information will be staged differently.
Hell, even in the books there are many things I would like explained.
I'm kind of curious of the series may turn out to give a few spoilers as it gets closer to the books. I can't see HBO being too pleased by the absence of Tyrion for a season. The 4th and 5th books are probably going to need to be merged for purposes of the series.