Fully agreeing with the previous reviewers who've already pointed out that this edition is probably not the best one quality-wise and also lacks from any serious accompanying notes, I'd just like to add the information that the superimposed American subtitles were apparently already on the analogue master this DVD copy is based on, and therefore they cannot be switched off.
They're also always white, and frequently there's white subtitles on bright background - useless: you can't read a thing. And they even have misspellings: they say 'toady' at one point instead of 'today'.
So overall, I'd say this edition is probably all right if you just want to get an idea what "Triumph of the Will" is all about, but if you value a quality reproduction and don't like cheap bargain basement editions, better stay away.