Soldiers dress in old fashioned costumes and perform old mortar drill.
Full title reads: "Woolwich. 'Like and old picture come to life'. Reproduction of firing a mortar battery of a hundred years ago - striking feature of this year's Searchlight Tattoo."
Men dressed in costume as 19th century soldiers. They stand by old fashioned cannon / mortars. The soldiers load mortars and they are fired (It looks more like fireworks going off than mortars). Shots of men dressed as old fashioned officers looking on. More shots of loading (if watched closely it can be seen how the fake is being done).
N.B. The Woolwich arena looks very empty suggesting that this may be film of a rehearsal rather than the performance.