This is the Brazilian national film archive, dedicated to the conservation of master copies of films of all kinds. It holds copies on DVD or videotape of a number of early films of ethnographic interest by Luiz Thomas Reis, Silvino Santos, Heinz Forthmann, Darcy Ribeiro and others, but the original materials of at least some of these appear to have been destroyed in a large fire in 1982.
In addition to an on-line data base of its current holdings, the Cinemateca also offers a comprehensive on-line data base of Brazilian films generally, including early ethnographic films that appear to have been definitively lost. This may be accessed here.