Flamethrowers had two fuel lines. The line he is lighting is cigarette with is sort of like a pilot line. It is a smaller fuel line that stays lit and can produce a bit of a larger flame when its trigger is pressed. The second line is for the big fire. This contains a thicker gelatinous type of fuel. So the flamer will pull the first trigger making the pilot flame larger, then pulls the second trigger emitting the thicker fuel which gets lit by the pilot flame raining hellfire upon anyone in its path. So technically its not really a blowtorch, but just a little pilot flame.