Zach,
Thanks. Yeah you are right. The example posted here seems to work just fine mainly because the height of the embed is static. I think if you 'edit on codepen' and change the height of the window then you'll see what I mean. All in all, it works fine until the window's height is changed by dragging it. That's when the calculations for the sprite sheet and the size of the scrub area misalign.
Thanks again.
j