here's my shot at a very simple motion blur effect:
it averages the costume's pixels with a shifted ("rotated") copy of itself:
another use case for my current hobby horse:
it's quite fast due to hyperblocks, and it can be made a lot nicer by creating not just 2 copies, but a set of copies, especially if the "motion" shift is bigger:
Of course, this will also make it a lot slower, especially for bigger pictures and / or higher offsets.