A film made by Donald Raymond Clark of the Middlesbrough College of Education Cine Club, viewable at the Yorkshire Film Archive. It's dated there as 1965, but you'll note the appearance of a bus new in 1966.....
There are a couple of distant views of Middlesbrough Corporation Daimler Fleetlines:
...but we see 74 (AXG674) in close up; it's a 1950 Eastern Coachworks bodied Guy Arab III:
50 (BXG750C) is a 1965 Daimler Fleetline with Northern Counties body; Middlesbrough specified the lower powered 6LW engine in most of their Fleetlines instead of the then more usual 6LX:
Passing is a Bristol KSW of United Automobile:
...and also this rarity, 1 (DXG401D), a 1966 Leyland Panther Cub/Northern Counties, one of a pair: