Layer 2 Y speed used in the scrolling codes, particularly in the Layer 2 scroll command (sprite EA).
#$0001-#$7FFF = move upwards; #$8000-#$FFFF = move downwards. #$0000 means there is no movement.
$7E:144D also controls the time until you can press a button to end the castle destruction sequence (after all text has been generated on-screen).