I think this is a period car, but maybe done up to look like a Gulf-Wyer team car. Did you see the Rotoflex couplings? I don't think many of the later cars have those, unless it is a Gelscoe GT40.
Great sound from the crossover exhaust system; gives me chills. Wish they had showed more of the car itself, like the engine compartment and the interior, etc. Nice video, though.