moistfinger: You are right that the rules are not written so that all the details are clear for someone not knowing the game.
Moreover, time to time there occurs a bug and therefore even a player who knows all the rules of this game can be surprised what the system (= BrainKing) allows to play.
However I think that the basic rules are clear enough (and if anyone gets in some suspicious position or situation, there are discussion boards such as this one to get help and advice).
I agree that the quotation you used
'... but does not have to jump over two or more pieces at once'
is not absolutely clear. The whole sentence is as follows:
'A queen does not have to land directly behind the captured piece, it can choose (when jumping) any other empty square in the line but does not have to jump over two or more pieces at once.'
I guess that this means, easily said, that before performing the second (and any other later) jump, you have to land... But you are right that the particukar quotation sounds somehow strange (especially when you MUST continue jumping if you have such an opportunity)...