I print screened this while watching the film on my laptop. To my untrained eye, it appears to be a Red Finsbury in the Personal Size? Though one of you out there may be more of an expert than me so this is purely a somewhat educated guess from me!
Speaking of Filofax sightings, I noticed that one of my lecturers' use a Pocket sized Filo. Never had the chance to see what model it was though but I thought that is pretty cool as I rarely see them at university!
EDIT: On second thoughts, that looks like a Red Finchley! How can I not have thought that to begin with. The distinctive clasp...and I own three of those bad boys!