Re: Can anyone guess what the focal length of the lens would be from this film clip?

It's reasonable to assume it's shot on super35 since it was a big budget film. With that in mind, an 85mm lens gives a working distance of 6ft which is nice for a dolly. Alternately, a 100mm lens at 7'6" could be an alternative. Both have been calculated with pCam for iPhone.

Regardless, they're both guesses as there really isn't a good depth cue for subject/background and so on.