It's a nice approximation, but it's also a hack—it doesn't take 'scrolloff' into account, and once you scroll too far in one of the windows they lose synchronisation.

Edit: You can record a macro to do something similar—create a vertical split, switch to it, disable scroll-bind, go forwards one screen, enable scrollbind, then switch to the other window. This doesn't lose synchronisation but it doesn't take 'scrolloff' into account either.