Hi - is it possible to apply two different colours to a paths stroke...so that when the path line is animated the colours move with the parts of the path they are applied to ? (I tried using the gradient stroke on a shape layer but it doesn't seem to work well when i move the point on the path to animate them).
you may be able to do what you are looking for with 2 instances of the stroke effect.
if you create a mask path on a layer, add the stroke effect and set the paint style to 'on transparent' (set the size and color as desired).
then duplicate that stroke effect on the same layer, but change the color and set the style to 'on original'. now if the change the start or end values of the second stroke effect, it should give you two colors on the same path.