Heloise, I saw the movie a few years ago and do not recall it in detail, so I will not address that particular interview in any specificity until I hear it again. However, to answer your question, I have to say that "yes", Jean Dominique had become quite critical of some of Aristide's ways; but his commitment (one could even say devotion) to the "Lavalas social movement" was and remains unquestioned at this point.
This issue that you raised is still raw and touches a lot of nerves in different quarters. For my part, I wish that Jean Dominique's widow, Michelle Montas, could elaborate on or elucidate the question from her point of view, but I doubt that this will happen at this time, given the high stakes of politics in Haiti and also her current post as spokesperson for the U.N. Secretary-General.
In any case, it is not so unusual for comrades-in-arms to differ in the course of a social revolution. Some hinted that this also happened at some point in time between Fidel Castro and Che Guevara. However, I don't know the extent of it, if it were true. I do know that Fidel Castro always speaks very highly of Che's role in the Cuban Revolution and their personal friendship.
There's always more than the eye can see. You have however raised a very pertinent question and I hope that whoever can shed more light on this issue will take the opportunity of doing so.