Click the game.
Pause the recording when there's 0:12 left.
Click Start Playing.
As soon as you start playing, press
Select 'Quit Game'.
Select 'Quit (Save)'.
Hit the boss once or twice to kill it. You'll need to shoot up with
whilst dodging shots from the left and right using the L-Stick.
This achievement will pop moments after level 3 starts after you killed the level 2 boss.