Robert Fothergill’s Countdown Canada (1970) “is a dramatized documentary of the day when Canada becomes part of the USA” says Anna St.Onge, my archivist colleague at York University, pointing out this digitization (from York’s 16 mm print) on YouTube. It features Barbara Frum, Barry Callaghan, Larry Zolf, Abraham Rotstein and others. The catalogue record has some details, and see also the York University obituary for Fothergill.
York’s Ross Building is used as Ottawa. The Ross ramp is long gone—it was demolished in 1988 so Vari Hall could be built.