c.1930 St. Stephen's College
The introduction to the film clip reads:
The Hon. W. J. Southorn dedicating new wing of St. Stevens College at Stanley.
I've found a newspaper reference to W. T. Southorn opening the new college buildings in 1930. I wonder if that's the event shown in the film, or if there was a later visit to open an extension to the original buildings?
[Update, 29 Aug 2011: Ms Cortia Chung, teacher at St. Stephen's, identifies the video as "our science building opening ceremony by acting governor Southorn."]