HLF

Sagais don't have such long body, you can freeze the frame and see the shape of the fish. The profile tends to fit a queenfish better. Sagais do break surface to attack small fishes too, but I don't think it's sagai in this video.

Cant really see really haha but could it be a mix I saw some round bodied ones and long streamlined ones

i heard mackerels are attracted to fast shiny objects so is it good to use a metal jig spoon?

Yeap, jigs and spoons will definitely work on mackerels.