The Imperial War Museum has a public archive of WW2 era military film shot by the AFPU (Army Film & Photographic Unit).
This is the home page : https://film.iwmcollections.org.uk/
There is plenty to explore on line here on Hong Kong and other locations of course. It looks like work in progress as not all the links have a film at the time of this post. But still worth a browse!
September 1945 shots of victory parades & street scenes of Des Vouex Rd.
https://www.iwm.org.uk/collections/item/object/1060013894
September 1945 Japanese Surrender at Govt House
https://film.iwmcollections.org.uk/record/19832
14 September 1945 Admiral Bruce Fraser tours Hong Kong
https://film.iwmcollections.org.uk/record/461
Andy