By James Brinsford A BBC staff member who shot the video message of the Princess of Wales announcing her cancer diagnosis has opened about the filming of the announcement and suggestions the footage was edited. Kate Middleton’s message aired before the Six O’Clock News on Friday. The mother-of-three revealed she has been diagnosed with cancer and is undergoing chemotherapy treatment after major abdominal surgery – though she refrained from saying what type of cancer she has. In the video, which was said to have been recorded on Wednesday, the future queen said: “In January, I underwent major a…