for some reason your c3p is just showing me a white screen with a red dot on it.
I would say, looking at that game slowed down, what you have there is a "snake" following the bullet.
i.e. make a very long side on triangle sprite that fades right to left. Cut it up into say 10-20 pieces.
then use these pieces in the frames of a sprite as the segments of a snake that follows the bullet around.
There should be a few snake examples on here somewhere. Generally it involves making an array for each bullet to record its positions at certain intervals as it moves. Then use these recorded coordinates to set the position , angle and length of each segment sprite every tick so they follow along after the bullet. as you will have a higher frame number the further the segment from the bullet it looks like it is a tracer fading away.
I could be wrong, there are a few ways to achive the same effect, but anyway another idea to try.