From the site where the video resides:
"The Art of Stained Glass. This is an old film made with the co-operation of James Powell and sons ( Whitefriars ) circa 1938. A video of this film was made a few years ago but it is no longer available. This video is not a copy but has been made from an original source. It has been made for the enjoyment of all lovers of Stained Glass . Regards Patrick "