How did the makers ... (Spoiler)

... manage to follow, up to the tournament, the very three people who happened to be the three finalists? Perhaps it was a case where they initially documented say, ten "favourites" on the assumption that there would be a good chance that within that group would be the three finalists. Or they filmed the tournament first and then documented the lives of the finalists afterward.

I wondered the same thing with Spellbound.