If you’ve ever tried to play an old analogue tape that has stretched with time, you’ll be familiar with the roll and vertical distortions that this filter creates.
0 to 1000
Shifts the video down in a simulation of bad tracking. Use keyframes to create an animated roll, if desired.
1 to 2000
Percentage based measure of how much of the vertical height of the image fits on the screen. A setting of 50, stretches the video so only half is on screen. A setting of 200 compresses the image so that 2 images fit on screen at once.