Over the years there have been a number of charters held on the HSR and the Hamilton area Radials. Often done in the early years as tours of the transit system or of the city of Hamilton for visiting dignitaries and transit industry professionals, in later years these trips were mostly by transit and rail fans both local and foreign.
Author's Note: This page will not cover charters done by the Canada Coach Lines, as they were a much more regular event as part of their business model. Also this will not cover extra services put on by the HSR handling special events such as extra bus services run on TiCat game days.
Summer 1945, National Railway Historical Society, HSR #125, 128, 502, 521, 417
While this footage is labelled as 1942, the Ontario license plate style seen in it dates it to 1945. (Also I think wartime secrecy would have prevented filming this much railway equipment). Footage from this trip is also found in Hamilton Street Railway - The Electric Years - 1892 to 1994 by GPS video, but it is misdated as 1947.
A brief summary of what you're seeing
May 7, 1972, North American Trackless Trolley Association, Brill T48A coach.
May 25, 1975, Toronto Transportation Society, HSR #748
July 1975, ?, HSR #750, 790
May 6, 1978, Toronto Transportation Society, HSR #85
June 13, 1998, Toronto Transportation Society, HSR #8201
September 2, 2006, Toronto Transportation Society, HSR #518203 and #518206
September 5, 2015, Toronto Transportation Society, HSR #1421
June 4 2016, Toronto Transportation Society, HSR #1503, 0301, 0320